Evapotranspiration is important for agricultural, environmental and other studies, and understanding the attribution of its change is helpful to provide information for climate change and water resources management. Based on the meteorological station-based data from 1961 to 2013, the Penman-Monteith (P-M) model is used to estimate the spatiotemporal distribution of the potential evaporation in the Middle and Lower Yangtze River Basin. And the inverse distance weighting (IDW) interpolation is used to demonstrate the spatiotemporal characteristics of PET. Furthermore, eight-day images of MOD16A2 are composited into monthly data, weighted by the number of days recorded in every month. And the MOD16/PET product during 2004-2013 are compared with the PET calculated by P-M equation. The results show that: 1)The annual PET value had decreasing trends before 2002, while had increasing trends from 2002 to 2013. 2)On the annual scale, the averaged PET was 885 mm. The annual change of seasonal PET had obvious differences; and the comparison is as follow: summer > spring > autumn >winter; 3)In the study area, the correlation values, the mean absolute error and the root mean square error between the PET value calculated by P-M model and the MOD16/PET product are 0.67, 10.4% and 0.31 mm/d, respectively, suggesting that the MOD16A2 product could better demonstrate the spatiotemporal distribution characteristics of the potential evapotranspiration.