With the widely extension of plastic mulch technique in Xinjiang region, the key problems, such as water and salt movement characteristics in isothermal and non-isothermal condition and the mechanics of plastic mulch technique which can prevent soil slat from moving to surface layer, haven't been probed moredeeply. Based on the experimental data of isothermal redistribution and evaporation with entirely plastic mulch of Xinjiang salinized soil for the same period, after infiltration with different wetting depths, their characteristics of soil water content profiles have been compared, and the results shows a little difference, which showed plastic mulch's significance on water saving; Base on that, the soil salt content and soil salt concentration profile are compared and shows a little difference too, which indicated that temperature gradient had no obvious influence on soil water and salt movement and showed plastic mulch's significance on anti-salinization. Later, the functional relations of soil salt content as well as soil salt concentration with vertical position and infiltration depth were developed. The researches in this paper showed the characteristics and mechanics of plastic mulch which preventing soil salt from moving to soil surface.