Biodiversity is the basis for maintaining ecosystem stability and adapting to environmental changes，and is also inseparable from human health. However，the causal path between urban and rural green land biodiversity and public health is still an important research gap. Taking Chengdu as an example，this paper discusses the relationship between urban and rural green land biodiversity and public health by using the quantitative research method of questionnaire survey. The results showed that the diversity of urban and rural green space animals and plants was significantly related to residents’ self assessed health and mental health. The natural relevance of residents is significantly related to the frequency of green space use and the evaluation of green space health benefits. Biodiversity is of great importance to public health，and the natural attributes of residents will also have a great impact on the use of green space，which provides a scientific basis for the formulation and management of public health policies for urban and rural construction. In the future park city construction，we should not only consider the benefits of biodiversity，but also attach importance to providing opportunities for the public to contact nature and receive natural education，so as to promote the symbiosis between man and nature and promote the sustainable development of urban and rural green space.