The purpose of this study was to investigate dynamic variations of soil water under the phreatic evaporation with different aperture ratios of plastic mulch. Based on column simulation laboratory indoors, HYDRUS-1D model was used to simulate variations of soil water content under different aperture ratios of plastic mulch and atmospheric evaporation capacity, and then the result was compared with the measured data.The results indicated that soil water content was affected by both aperture ratio of plastic mulch and atmospheric evaporation capacity.The soil water content decreased with the increase of the aperture ratios of plastic mulch and atmospheric evaporation capacity with the same depth of soil profile. The fluctuations of soil water content in the upper layer was more obvious than that in the lower layer. When the aperture ratio of plastic mulch and atmospheric evaporation capacity was fixed, the soil water content increased in the early evaporation period and remained stable in the later evaporation period. The evaporation was obviously inhibited by plastic mulch, but when the opening rate of mulching increases to a certain value, the effect of surface salinity on soil evaporation is greater than that of mulching. Mulching increases soil moisture content and decreases cumulative evaporation. The simulation precision of model which was checked by the measured data was well. So it is feasible with HYDRUS-1D model to simulate soil water movement under different aperture ratios of plastic mulch.