Abstract: Studies have shown that rainfall floods are closely related to geological disasters such as landslides and mudslides in mountainous cities. Thus, improving the ability to adapt to rainfall flood disasters has become vital for dealing with the frequent occurrence of secondary disasters in mountainous cities. Based on the disaster chain theory, this paper analyzes and summarizes the disaster chain of mountain rainfall floods, the chain-style disaster evolution relationship, and the disaster path around the three key elements of a disaster chain: disaster-inducing factors, disaster-formative environments, and disaster-affected bodies. On this basis, we put forward strategies to reduce rainfall flood-related damages. Our study is based on “disaster chain breakage” and “urban space disaster reduction”, to reduce the frequency of rainfall flood disaster chains and disaster amplification, and increase urban safety. Taking the urban design of Zaoyang New District in Wushan County as an example, we investigated the practical application of the strategies for flood prevention and disaster reduction, so as to provide corresponding theoretical guidance and practical reference for the construction of disaster prevention and damage reduction capacity in mountainous cities.