Evapotranspiration is the key link between the atmospheric process and terrestrial hydrological process, which plays an important role in water cycle processes and water balance on the regional/basin scales. In karst area, suface ecological environment is fragile and sensitive to climate change. Evapotranspiration may be the key eco- hydrological process associated with atmospheric, water, energy exchange and carbon cycle. Therefore, accurate estimation of evapotranspiration plays an important role in better understand of the karst water cycle in response to climate change, carbon cycle and ecological restoration. In this study, the potential evapotranspiration ET 0 in Guilin city was calculated by using the Penman- Monterith method based on the daily meteorological data from Guilin meteorological station during the period from 1951 to 2015. The Mann- Kendall test and correlation analysis were used to determine the trend of potential evapotranspiration and its influencing factors in Guilin city. Results show that potential evapotranspiration in Guilin has a significant annual, interannual and seasonal changes. The ET 0 in Guilin from 1951 to 2015 had a significant decreasing trend with a rate of -8.02 mm/10a on the annual scale. Decreasing trends were observed in summer, autumn and winter, while a slightly increaseing trend was observed in spring. Significant annual decreasing trend of ET 0 in Guilin could be concluded as mostly affected by the decline of summer ET 0 . Abrupt changes for ET 0 series were detected in 1967 and 2003. The results of Mann- Kendall trend test and correlation analysis show that average, maximum and minimum air temperatures have increased significantly over the past 65 years, whilst wind speed, relative humidity and sunshine duration exhibited significant decreasing trends. Sunshine duration was the major factor dominating variability of ET 0 in Guilin from 1951 to 2015, followed by wind speed.