Evapotranspiration is a key element of hydrological cycle and water balance. It is of great significance to study its spatial and temporal variation law for the optimal allocation of water resources in the basin. The SEBAL model combined with the reference evaporation ratio was used to simulate the evapotranspiration in the Ziya River Basin from 2001 to 2020. The Mann-Kendall trend test and the coefficient of variation method were used to analyze the temporal and spatial variation characteristics. The correlation analysis, partial correlation analysis and path analysis were used to explore the influencing factors of evapotranspiration change. The results show that : (1) The relative error between the evapotranspiration simulated by the SEBAL model and the measured evapotranspiration data of the eddy correlation system is -7.5%, and the relative error with the water balance calculation result of the sub-watershed is -9.6 %. (2) The annual average evapotranspiration of Ziya River Basin is 520.3 mm/a, which shows an upward trend in spring, summer and autumn, with little overall change in winter, and the annual evapotranspiration shows a single peak, mainly concentrated in May-July. (3) The overall spatial distribution characteristics of evapo-transpiration in the basin are high in the west and low in the east. Under different underlying surface types, the an-nual evapotranspiration of water body is the largest, followed by forest land and grassland, and farmland and urban land are the lowest. (4) The change of evapotranspiration in the basin is directly influenced by net radiation and air temperature, and indirectly influenced by air pressure.