By changing the underlying surface conditions, vegetation change can regulate the distribution ratio of vegetation transpiration to soil evaporation, and then change the regional and even global water cycle process, and have a profound impact on the sustainable development and utilization of water resources. Since the 1990s, China has carried out a large-scale vegetation restoration project, which has greatly increased the vegetation coverage, especially in the middle reaches of the Yellow River. In this paper, six typical vegetation restoration watersheds in the middle reaches of the Yellow River Basin as the research object, using meteorological and hydrological data, verify the performance of the PML_V2 model, and analyze in the vegetation restoration project background, from 2003 to 2018, the evapotranspiration in the middle reaches of the Yellow River (ET) and its components (Ec vegetation transpiration, Ei intercept evaporation, Es soil evaporation) change pattern of space and time. (1) By comparing the results of ET and PML models, it is found that this model has good applicability in the middle reaches of the Yellow River (NSE >0.6). (2) Ec plays a leading role in the distribution pattern of ET, which is controlled by the spatial distribution of vegetation under the action of summer monsoon. The spatial distribution pattern of Ec and ET is similar, while that of Es is opposite. ET, Ec, Ei all showed a significant increasing trend, while Es showed a significant decreasing trend, especially in the middle and lower reaches of the basin. (3) In the context of vegetation restoration, ET and its components in the typical watershed of the middle reaches of the Yellow River change significantly. Compared with their located watersheds, ET, Ec, Es and Ei are 2.20%, 5.86%, 0.86% and 7.44% higher, respectively, and the rates are -0.51 mm/a, 0.55 mm/a, -1.11 mm/a and 0.05 mm/a higher, respectively.

Keywords： Middle Yellow River; evapotranspiration; PML_V2 model; vegetation restoration; change of time and space