The uncertainties of evapotranspiration (ET) products developed based on satellite remote sensing and observations with different spatial and temporal resolutions still exist in the Tibetan Plateau (TP), limiting the application in hydrometeorological and climate assessment. Six ET (PML, EB-ET_V2, GLEAM, GLDAS, ERA5 and MOD16) products were evaluated based on eddy observations and the differences between the products were compared, and the uncertainty of ET products in the TP region was analyzed. The results show that: (1) There is a good correlation and consistency between the flux towers and the ET products of the corresponding pixel, and the seasonal changes can be captured. GLEAM has a high degree of agreement with the measurements and has applicability. MOD16 has poor performance at most sites. (2) Spatially, GLEAM has higher correlation (the correlation coefficient, R>0.88) and consistency (Index of agreement, IOA>0.89) with EB-ET_V2 and GLDAS. There are big differences in the temporal and spatial distribution of various products in the seasons, especially in spring. Compared with other products, MOD16 is underestimated in summer and overestimated in winter in most regions. (3) The annual average ET of each product except MOD16 is quite different. The ranking of the average ET for many years is ERA5 (401.46mm/year)>PML (334.37mm/year)>GLEAM (298.46mm/year)>EB-ET_V2 (271.39mm/year)>GLDAS (249.67mm/year). The total annual evaporation in the effective area is 330.59mm/year. The assessment results table helps to have a deeper understanding of the quality and dynamics of ET products on the TP, which can provide a reference for water resources assessment and regional water management on the TP.