Ecological land guarantees the stability of urban ecosystem structure and function. In the background of rapid urban development and the constraints of available land resources, Beijing has explored many effective ways to coordinate ecological protection and urban development under the framework of the city master plan. To provide a reference for the synchronized planning and coordinated layout of ecological land and construction land, it is necessary to analyze the spatial and temporal characteristics of ecological land change. In response to the inadequacy of the existing studies on ecological land, this paper considered the city as a whole, not only focusing on ecological land itself, but in the framework of a comprehensive analysis of the interconversion of ecological and other types of land. Based on the GlobeLand30 land cover data of Beijing in 2000, 2010 and 2020, this paper analyzed the interconversion of ecological land, construction land and agricultural land from 2000 to 2020, revealing the spatial distribution characteristics of land change intensity of various land use types at different distances and orientations. Moreover, we further depicted the spatial and morphological pattern of ecological land changes using Landscape Pattern Index. We modified the landscape expansion index (LEI) to landscape expansion/shrink index (LESI) to reveal the spatial change pattern of ecological land both the increasing part (e.g., outlying and edge-expansion growth) and the decreasing part (e.g., extinction, fragmentation and shrink pattern). In addition, the accessibility of construction land and ecological land was calculated by Gaussian based on 2-step floating catchment area (2SFCA) method. The results showed that:(1) the proportion of ecological land area has been maintained at 13%-15% from 2000 to 2020. Despite the rapid expansion of construction land, ecological land has not grown in tandem. However, the spatial distribution of ecological land at different distances and orientations has changed significantly. The areas with better ecological conditions were negatively affected by urban growth, while areas with worse ecological conditions were strengthened in the ecological construction of urban growth. (2) The spatial distribution of ecological land tended to be disperse. The increasing parts were identified as the outlying and edge-expansion growth patterns, while the decreasing parts changed from the extinction pattern to the fragmentation and shrink patterns. (3) The accessibility of construction land and ecological land was generally low during the study period. From 2000 to 2010, there were more new construction lands with low grade of accessibility than existing construction land, while the areas with high grade of accessibility were scattered in the central areas of the city; from 2010 to 2020, there were more new construction lands with high grade of accessibility than existing construction land, and the spatial distribution of higher accessibility areas was more uniform. Focusing on the spatial and temporal changes of ecological land from 2000 to 2020, this paper revealed the mutual interconversion intensity and spatial morphological changes of ecological land, construction land and agricultural land under the background of rapid urban growth, providing practical reference in solving the contradiction between urban growth and ecological construction.