In order to better carry out the ecological protection and restoration of the wetland in the lower reaches of the Yangtze River, the authors selected the Landsat images of Shengjin Lake in different seasons from 2000 to 2019 as the research data with the support of Google Earth Engine (GEE) cloud platform. The land surface temperature (LST) was retrieved by a batch program using radiative transfer equation method. The spatio-temporal variation of LST and its responses to land cover in Shengjin Lake during the past 20 years were comprehensively analyzed. The results are as follows: ① From the perspective of space, the spatial distribution of different temperature grades has shown obvious differences with the seasonal changes. The high-temperature region is dispersed in spring, generally located in the northwest in summer and autumn, and mostly in the south in winter. The area of the lake varies with the seasons, but its temperature belongs to very low or low temperature grade at all seasons. ② From the perspective of time, in the past 20 years, affected by forest and water, the Shengjin Lake wetland has always been dominated by the medium and low temperature grades that account for a large proportion of 70%-85% or so. The area proportion of temperature grades varies with the time trend such as seasons and years. ③ There exist seasonal differences in the responses of LST to land cover. It is basically presented in the form of a descending order of artificial surface> cultivated land> forest and mudflat> water. ④ Non-urbanization factors have a certain impact on the surface temperature of natural wetland. The research results are certainly significant for the reasonable development of Shengjin Lake.