[Objective] Land use change and its impacts on the ecological environment of the urban agglomeration of Chengdu Plain under the influence of rapid urbanization were analyzed and measured in order to provide a theoretical basis for optimizing land use structure and ecological environment management in the region. [Methods] Based on land use data from 2000 to 2019, the characteristics of land use changes in space and time for the urban agglomeration of Chengdu Plain were analyzed. The ecological effects of land use changes were then analyzed quantitatively in the region. [Results] ① The area of land use change in the urban agglomeration of Chengdu Plain from 2000 to 2019 showed typical characteristics of “four increases and two decreases”, of which the largest increase and decrease were construction land (an increase of 1 704.59 km²) and cultivated land (decrease 911.04 km²), respectively. In addition, the construction land and waters changed significantly over time. ② During 2000—2019, forest land had been the most important ecological land in the urban agglomeration, and its importance was as high as 53.81%, while the importance of the ecological value of construction land, water area, and unused land did not exceed 2%. In the state of urban expansion under the following conditions, changes in the four types of land use of cultivated land, forest land, construction land, and grassland had a greater impact on the ecology of the region, and the total ecological value contribution rate of changes in land use was 94.76%. ③ The ecological environment index of the urban agglomeration during the study period showed a pattern of decreasing first and then increasing. In general, the quality of the ecological environment in the region remained dynamic and stable, showing a relatively upward trend after 2015. [Conclusion] The government should control land use patterns, make intensive use of construction land, protect the quality and quantity of cultivated land, focus on implementing policies to protect forests and grasslands, and restore and improve the ecological environment of the urban agglomeration of Chengdu Plain, so as to enhance the sustainability of urban agglomeration development effectively.