With the rapid development of urbanization, urban ecology has entered an unprecedented period of prosperity, and some new concepts and paradigms have drawn wide attention. We analyzed the characteristics of component, structure, processes, functions, and services from the perspective of ecosystem and proposed the "black box" paradigm and "structure-process-function-service cascade" paradigm for urban ecosystem research. We also explored different roles of human and nature in the component, structure, process, function and services of urban ecosystem, discussed the interactive mechanisms between human and nature by mosaic component, fused structure, coupled process, complementary function, and synergized service within urban ecosystem. It is proposed the paradigm of co-evolution of human and nature for urban ecosystem research. It will provide important theoretical support for the in-depth understanding and research of urban ecosystem.