Green infrastructure (GI) refers to a coherent planning green space, which consists of all-natural, semi-natural, and artificial networks of multifunctional ecological systems within, around, and between urban areas, at all spatial scales. It is an indispensable support for urban development and normal operation. With the rapid development of urbanization, irrational development and construction methods such as disorderly urban sprawl and massive consumption of natural resources, aggravate a series of urban ecological and environmental problems such as rainstorm and flood, haze, water pollution, heat island effect, and so on. The original landscape could not be maintained coherent due to construction, and the connectivity and integrity are destroyed, weakening the ability of sustainable development. The contradiction between human activities and the ecological environment becomes increasingly prominent. The emergence of urban ecological problems has reaffirmed GI's service function and security action, as well as an effective way to solve the ecological and environmental problems and promote urban green development. On the whole, studies on GI have achieved abundant results, but most of them focus on the analysis of the structure and changes of specific elements of GI, and relatively little attention is paid to the spatial and temporal pattern changes of GI from the perspective of geography, and few studies are focused on the evolution of different types of elements. By using the method of morphological spatial analysis and GIS technology, this paper takes Nanjing as an example to measure the spatial and temporal changes of GI from the aspects of overall scale, network connectivity, and its components, and to analyze the driving factors. The results showed that the overall scale of GI in Nanjing increased first and decreased later from 2000 to 2020, while the network connectivity decreased. The area of natural ecological elements in Nanjing decreased due to the shrinkage of large patches in Gaochun, Lihe, and Qixia Districts; Semi-natural and artificial factors increased in scattered small patches, expanding from the central area to the periphery. The change of GI pattern in Nanjing is influenced by natural endowment conditions, regional development level, social and cultural atmosphere, and the orientation of decision-making and management. The spatial and temporal differences determine the different changes of GI construction and development in different regions. Among these, natural endowment conditions such as topography, climate, and hydrology play a basic role, the regional development level such as population, industry, and input are the main driving forces, whereas the social and cultural atmosphere and the orientation of decision-making and management play a guiding role.