Research the change of potential evapotranspiration and its sensitivity,it is of great significance for agricultural sustainable development and protection of the ecological environment. This article use Penman- Monteith method and sensitivity coefficient method to analyze spatial and temporal variation of potential evapotranspiration and sensitivity of potential evapotranspiration to average temperature,wind speed,solar radiation,and vapor pressure from 1965 to 2014 in Liaoning Province. It aimed to investigate the dominant factors affecting the potential evapotranspiration and the quantitative response of potential evapotranspiration to climate change. The results showed that: Nearly 50 years potential evapotranspiration showed a significant decrease trend. In space,it presented by the west to east decreasing trend. The reference evapotranspiration was most sensitive to vapor pressure,which is followed by solar radiation and wind speed,average temperature on an annual scale. In terms of season,average temperature was the least sensitive variable in spring and autumn,wind speed was the least sensitive variable in summer and solar radiation was the least sensitive variable in winter. Spatially speaking,spatial variation of meteorological factors and its sensitivity coefficient are consistent during the year. Sensitivity to the temperature of the potential evaporation is increasing north to the south,sensitivity to the vapor pressure and solar radiation of the potential evaporation is decreasing east to west,but the change of wind speed is opposite. The main reasons for the decrease of potential evapotranspiration in Liaoning Province are the significant decrease of wind speed,and the decrease of solar radiation and the increase of vapor pressure also contribution to the decrease of potential evapotranspiration.