Abstract: Investigating the evapotranspiration (ET) in the Huaihe River Basin and its relationship with meteorological factors holds significant importance for predicting drought trends and optimizing agricultural water allocation. Based on the measured ET (ET_m) in farmland from the weighing lysimeter during 2017—2019, this study analyzed the ET changes under the winter wheat-summer maize crop rotations and examined the applicability of the simultaneous MOD16A2 ET and potential evapotranspiration (PET) products in the Huaihe River Basin. Besides, it explored the characteristics and trends of PET in the basin using the trend analysis method and analyzed the correlations between meteorological factors and PET by calculating their Pearson correlation coefficients. The results show that the ET_m exhibited a bimodal distribution pattern, with two significant peaks corresponding to the growing seasons of winter wheat and summer maize (April and July), respectively. The ET_m, ranging from 868.8 to 1 116.3 mm, is characterized by considerable interannual variations and significant correlations with the ET and PET. The Huaihe River Basin showed a west-to-east decreasing gradient in average PET. The average PET within the basin reached its minimum in 2003 (1 316.7 mm/a) and its maximum in 2019 (1 868.8 mm/a), yielding a considerable difference of 552.1 mm. Moreover, the basin witnessed a multi-year PET decrease in the northwest and an increase in the southeast, with the slope trending upward generally and average 0.99. Within the basin, May recorded the highest multi-year average PET, while January saw the lowest value, with the overall PET in winter still lower than that in other seasons. The PET in most areas of the Huaihe River Basin had a positive correlation with temperature and a negative correlation with relative humidity.