[Objective] The spatiotemporal change characteristics of land use pattern and the effect of ecological environment in Fushun City, Liaoning Province after returning farmland to forestland were discussed, in order to provide reference for the optimization of land use structure in this area.[Methods] Based on the remote sensing images in 2000, 2010 and 2020, the spatial and temporal change characteristics of land use pattern and the ecological environment effect in Fushun City were quantitatively analyzed by using the methods of land use dynamic degree, land use degree comprehensive index, land use transfer matrix, NDVI difference analysis and regional ecological environment quality index.[Results] ① From 2000 to 2020, there was a mutual transformation relationship between various land types in the study area, among which, the change of woodland and cultivated land was more obvious. During the past 20 years, the area of cultivated land decreased by 825.59 km², with a growth rate of -7.32%. Forest land area increased by 591.14 km², with a growth rate of 5.24%. Urban land area increased by 182.36 km², with a growth rate of 1.62%. ② In 2000, 2010 and 2020, the comprehensive index of land use degree in the study area was 224.48, 225.57 and 226.12, respectively, with year-on-year growth of 0.49% and 0.24%. The intensity of land development and utilization in the study area increased slowly. ③ During the past 20 years, the vegetation coverage in the study area showed an upward trend. The decreased areas of NDVI basically coincided with the expanding areas of urban land. ④ The environmental quality index of land use transition in the three periods were 0.744 8, 0.775 4 and 0.782 6, respectively. During the past 10 years, the environmental quality index increased by 4.11% and 0.93%, respectively, and the overall environmental quality showed an upward trend.[Conclusion] In the past 20 years, the rapid urbanization process in the study area has been promoted, the overall environmental quality has been improved, and the improvement and deterioration of ecological environmental quality coexist in some local areas. The transformation among urban land, cultivated land and woodland is the main reason. The environmental protection policies such as returning arable land to forest make the environmental quality in the study area continuously improve. But the upward trend flattens out over time.