Abstract: The demand for green, low-carbon and sustainable spatial development has brought the concept of urban nature into focus. In this context, the comprehensive connotations and cutting-edge results thereof in urgent need of systematic interpretation. This research elaborates on the four development phases the aforesaid concept has experienced in Germany, namely the preparation, formation, identification and breakthrough phases. Based on this, the research, through comparative analysis, discusses not only the cognition of urban nature from the perspectives of ecology and landscape architecture during the preparation, formation and identification phases, but also the new trend of development brought about by the increase of public natural awareness and the implementation of the Overall Planning of Urban Nature (German: Masterplan Stadtnatur) during the breakthrough phase. Furthermore, through logical inference, it proposes the cognitive framework of ‘biology-human-society-climate-ecology’ for urban nature in the 21st century based on the essence of measures specified in the Overall Planning of Urban Nature, which explains the important contents of urban nature in terms of core, medium, link, challenge and facility. Drawing on German experience, the research puts forward the following viewpoints: 1) integrate the multi-layered connotation of urban nature to build a comprehensive cognitive system; 2) build a complete urban nature planning and implementation system under the guidance of laws and regulations; 3) carry out diversified consultations and focus on multi-stakeholder participation and cooperation, thus contributing essential ideas and enlightenments to the research on urban nature in China.