Based on a pair of black and white standard A-type evaporation pans set under the same meteorological conditions, the dynamic characteristics of meteorological elements, water temperature and evaporation of the two pans were observed. The influence of water temperature on the evaporation of the evaporation pan was explored based on the existing 6 evaporation models. The results showed that 1) the designed observation method can be used to study the effect of water temperature on the pan evaporation. The water temperature and evaporation rate between the two pans were significantly different. During the 50-day observation period, the average water temperature difference between the two pans was 0.4°C, and the average daily evaporation difference was 1.1 mm/d. 2) 1°C increase in water temperature difference between black and white pans will produce an evaporation difference of 0.808 mm/d under the same conditions of solar radiation and other meteorological elements. 3) Under the condition of rising water temperature, the estimated value of the classical evaporation model without considering the water temperature would be smaller than the actual observed value, and the error of the estimation will also increase correspondingly.