With the methods of linear analysis and correlation analysis, the tendency rate of the ground temperature for about 50 years in Puyang and the causes are analyzed. The results indicate that the monthly mean ground temperature has an obvious rise trend from December to next April, and a drop trend from May to November, with the tendency rate being 0.01 to 0.32 ℃ per 10 years and -0.04 to 0.83 ℃ per 10 years. The tendency rate of the annual mean ground temperature is -0.23 ℃ per 10 years; that of the monthly mean maximum temperature in November is 0.01 ℃ per 10 years, and -0.46 to -2.16 ℃ per 10 years in the other months; the annual mean temperature -0.23 ℃ per 10 years; the monthly mean minimum ground temperature in November -0.02 ℃ per 10 years, and 0.09 to 0.76 ℃ per 10 years in the other months; the annual variation 0.34 ℃ per 10 years; the monthly mean airground temperature difference is -0.17 to -0.66 ℃ per 10 years, and annual mean airground temperature difference -0.35 ℃ per 10 years. It can be concluded that the average maximum ground temperature has a yearbyyear drop trend, and the average minimum ground temperatures has a yearbyyear rise trend, with the variation range of the former being far greater than that of the latter. The annual mean ground temperature has also has a yearbyyear drop trend, resulting in less airground temperature difference and greater atmospheric stability, which are unfavorable for the spreading of pollutants and water vapor in the near surface. The variations such as the increased foggy days, heavier air pollution, decreased sunshine duration, and less solar radiation, are the direct causes of ground temperature drop, and the variations such as increased air humidity and precipitation and heavier air pollution are the indirect causes.