Abstract: To explore the law of land use transformation and its ecological effects in the context of rapid urbanization in Suzhou, using the land use data of the city for 4 periods in 1980, 2000, 2010 and 2018, and according to the classification of the dominant functions of production-ecological-living (PEL), the methods of the land use transfer matrix, ecological environment quality index, and ecological contribution rate of land use transformation were used to quantitatively analyze the pattern of land use transformation and its ecological effects in Suzhou City, and the driving mechanism of ecological environment quality evolution was revealed through least square regression. The results showed that: from 1980 to 2018, the transformation of land use in Suzhou City displayed a decrease in productive land use, a small increase in ecological land use, and a rapid increase in living land use; the quality index of Suzhou ecological environment decreased from 0.431 2 in 1980 to 0.4139 in 2018, and the overall ecological environment quality decreased. There were both trends of ecological environment improvement and deterioration in Suzhou City. In 1980-2000, the conversion of agricultural production land into watershed ecological land and woodland ecological land was the main factor contributing to the improvement of ecological environment quality. The crowding of agricultural production land into watershed ecological land and the occupation of agricultural production land by towns and rural living land were the main reasons for the deterioration of ecological environment quality. In 2000-2018, the conversion of agricultural production land into watershed ecological land was the main factor for the improvement of ecological environment quality, and the crowding of agricultural production land by towns and rural living land was an important reason for the deterioration of ecological environment quality. The adjustment of industrial structure and energy structure was the main factor for the improvement of ecological environment quality in Suzhou City, while the increase of population, unreasonable economic development mode, the increase of social consumption level and other factors increased the pressure on ecological environment protection.