Hongjiannao Lake is the largest desert freshwater lake in China. In recent decades，the area of the lake has sharply decreased. The evaporation of the lake surface is the main factor consuming its water volume. There‐ fore，this paper aims to reveal the characteristics of evaporation changes and the mechanism of the driving factors. Currently，most studies on Hongjiannao Lake directly use or convert the evaporation data observed at meteorological stations，which have many missing and discontinuous data，and do not qualitatively and quantitatively analyze the meteorological factors influencing the evaporation changes of Hongjiannao Lake. To address these is‐ sues，this paper uses the data converted from meteorological stations，calculates the evaporation using the FAO （P-M）formula，and simulates the evaporation using the CLM-LISSS model to obtain the evaporation data of Hongjiannao Lake. Through comparison with the converted evaporation data from meteorological stations，it is found that the evaporation values and correlations simulated by the CLM-LISSS model are closer to the actual situation than the results calculated by the FAO（P-M）formula. The evaporation simulation results based on the preferred model showed that the average annual value of simulated evaporation of Hongjiannao lake from 1980 to 2018 was 1004. 56 mm，and the M-K mutation test did not find the mutation year，and the overall trend was significantly upward（3. 01 mm·a-1）. The meteorological factors that have significant positive correlation with evaporation are air temperature，wind speed and downward long-wave radiation，and their correlation with evaporation and their own change trend pass the significance test of 95%. The sensitivity coefficient of evaporation to meteorological factors and the contribution of each meteorological factor to evaporation change were quantitatively analyzed by the formula calculation method and the perturbation analysis method of climate state respectively. The meteorological factors with greater contribution obtained by the two methods were significantly consistent with the correlation，and they were all air temperature，wind speed and downward long-wave radiation. However，the contribution ranking obtained by these two methods is slightly different and the contribution values of each factor are significantly different. This is mainly due to the fact that the change of evaporation is only caused by the change of a single factor，which reduces the influence of other driving factors，and effectively reduces the error between the change value of evaporation trend and the contribution sum of meteorological factors，from 128. 40 mm（109. 40%）to 56. 83 mm（48. 42%）. The perturbation analysis of climate state is superior to the formula calculation method in both mechanism and error. The results show that the contribution of meteorological factors to evaporation changes from large to small are downward long-wave radiation（71. 47%），temperature （59. 83%），wind speed（41. 00%），air pressure（1. 54%），downward short-wave radiation（-3. 00%）and specific humidity（-22. 43%）.