With the acceleration of climate warming and urbanization, the heat island effect is intensifying. How to take effective measures to mitigate the heat island effect on the basis of quantitative evaluation had become an urgent problem to be solved. Based on annual average temperature of national meteorological stations in Yinchuan and its surroundings from 1961 to 2022 and the data of Landsat8 in summer from 2017 to 2021, the relationship between heat island intensity and urbanization process in Yinchuan urban area was analyzed. The typical high temperature processes were selected, and the cooling effect of different buffer distances of lake wetland was evaluated quantitatively aiming at the lake wetland which could effectively alleviate the urban thermal environment. The results show that the effect of urban heat island was not obvious during 1961-2000 in Yinchuan, but after 2000, the average temperature and warming rate were significantly higher than those of reference stations, indicating that the effect of urban heat island was obvious. The correlation coefficient between heat island intensity and urbanization level reached 0.78, which passed the 0.01 significance test and showed a positive correlation. The typical lake wetland in Yinchuan urban area had obvious cooling effect during the summer high temperature processes, especially the surface temperature cooling effect within 500 m, in which the surface temperature dropped the most (up to 2.5 ℃) within 100 m, and the cooling range gradually decreased with the increase of distance from the water body. The average land surface temperature drops by 0.5 ℃ in the distance of 400-500 m.