Abstract: ObjectivePromoting the construction of all-age friendly cities is an important measure to practice high-quality development. Citizens could take long-term, numerous and diverse outdoor activities in urban comprehensive parks. Promoting all-age friendliness of urban comprehensive parks is an important aspect of effectively implementing the construction of all-age friendly cities. The construction of all-age-friendly urban comprehensive parks can provide all-age people with open spaces which have comfortable and vibrant environments. In addition, it can also create intergenerational activities and promote the physical and mental health of all people. At present, the degree of all-age friendliness of urban comprehensive parks is relatively low. The problems still exist, such as unbalanced distribution of activity quantity, activity types, and activity space among different age groups, as well as significant differences in activity quality. The purpose of this paper is to provide a scientific basis for the construction of all-age-friendly urban comprehensive parks by studying the all-age friendliness evaluation method of urban comprehensive parks. Methods This research constructs a quantitative evaluation method for the all-age friendliness of comprehensive parks from two dimensions including crowd activity and material space. First of all, the evaluation model and method of all-age friendliness of crowd activities in comprehensive parks through activity characterization are constructed. Next, the evaluation index system and method of all-age friendliness of physical space which is based on the relationship between the needs of all-age people and the elements of parks’ planning and design are constructed. The evaluation system of all-age friendliness of crowd activities and physical space complement each other. As a result, a relatively complete evaluation method of all-age friendliness of comprehensive parks can be constructed. Results At the level of crowd activities, this research constructs the evaluation indicators and measurement methods such as the friendliness of the crowd age structure, the friendliness of the crowd activity type, the friendliness of the crowd activity spatial distribution and the friendliness of the crowd activity quality. In physical space we establish the evaluation index system of all-age friendliness of physical space, which including 7 first-level indicators, 13 second-level indicators and 47 third-level indicators. This research takes four types of comprehensive parks in Xiamen as examples for empirical research. Based on the evaluation of crowd activities in four parks, it is found that there are differences in the all-age friendliness of different types of comprehensive parks: 1) Haiwan park attracts diverse group activities with beautiful coastal landscape and many recreational facilities, and has the highest all-age friendliness, but its elderly friendliness is relatively poor; 2) Zhongshan Park in the old city attracts more citizens, is more inclusive towards the elderly and children, and has a higher all-age friendliness degree. However, there are shortcomings in the age structure and activity quality of the active people. On the one hand, there is a lack of space for young and middle-aged people. On the other hand, there is a large playground space, and the activity quality of companion groups is low and intergenerational sharing is weak; 3) The space environment of Nanhu Park on the lakeside attracts people of all ages to carry out activities, but the proportion of individual activities and social activities is quite different from the expected value, and the interactive space affects the use of quiet rest space; 4) The complex terrain of Jinbang Park in mountainous areas limits the setting of activity venues, resulting in the lowest all-age friendliness, manifested by the low age structure and spatial distribution friendliness of the crowd. In addition, there are also significant differences in activity friendliness among different age groups in the parks: 1) The parks have the highest activity friendliness to the elderly group, which appears as the closest percentage of the number of people to the ideal value, the highest friendliness evaluation of spatial distribution, and the higher friendliness of the activity type and activity quality; 2) The parks have a higher activity friendliness to the children"s group, which is marked by the higher activity type friendliness and better activity quality friendliness. But there is a large variation of other indicators among different parks; 3) The park"s activity friendliness to the middle-aged group is low, because there is a large difference between the percentage of actual number and the ideal number of people, and the friendliness of activity space distribution and activity quality are both relatively low; 4) The parks" activity friendliness to the youth group is the lowest, as all indicators except for the activity type are at a relatively low level. Conclusion The research results on the age friendliness of crowd activities and material space are basically consistent. The indicators of crowd activities and material space complement, couple, and verify each other. The synergy of the two can effectively evaluate the all-age friendliness of comprehensive parks. This method provides a new approach for evaluating the all-age friendliness of urban public spaces and provides a scientific basis for the planning, construction, and management of urban comprehensive parks. The all-age friendliness evaluation of urban comprehensive parks should not only focus on external indicators such as the number and area of activities for different age groups, but also comprehensively consider internal indicators such as activity type and quality. It is suggested to optimize the planning of urban comprehensive parks in terms of functional layout, access system, spatial site, landsense creation and evaluation mechanism in the future, apply the age friendly index system to implement program evaluation, built environment evaluation and other aspects, and coordinate innovative implementation mechanisms for urban renewal, quality improvement actions and other projects to effectively promote the construction of age friendly parks and achieve high-quality urban development.