Based on the daily atmospheric temperature,air pressure,precipitation and other weather data of 22 weather stations in Beijing - Tianjin - Hebei region from 1960 to 2010,we calculated the daily potential evapotranspiration by using the Penman formula. The spatial variation,climate change,decadal variability,and the MK mutation testing were discussed in our paper. The results showed that the atmospheric temperature was increasing evidently in recent 50 years. The precipitation of most area was decreasing;the decreasing trend in east area was evident. The potential evapotranspiration in whole region was decreasing. The change of atmospheric temperature and precipitation caused aridity in the region,but the decreasing of potential evapotranspiration may relieve some drought trend.