To clarify the influence of different sand-soil mixtures on the soil evaporation process,on the basis of soil evaporation theory and micro-lysimeter field experiment,the dynamic changes characteristics of soil evaporation intensity and its action mechanism under six mixed sand-soil mulching patterns (1.0,0.8,0.6,0.4,0.2,0,denoted by M1~M6,respectively) were deeply explored.The results showed that the theoretical simulation of soil evaporation could realistically reflect the soil water evaporation under the mixed cover of sand and soil,and its cumulative evaporation could be quantitatively expressed by the mixing volume ratio of sand and soil evaporation time.There were only two prominent evaporation stages with significant evaporation inhibition when the the sand mixing ratio increased to above 0.8.When the mixing volume ratio of sand was decreased to below 0.5,the peak of soil evaporation stability stage under M3~M6 treatment had been concentrated in the first 2.53~2.66 d,and the main moisture dissipation duration was increased by 6.49,6.49,6.49 and 7.09 d compared with M1,respectively.However,when the sand mixing volume ration was between 0.5 and 0.8,the mulch layer was easily induced and could form the dense mulch dry layer earlier,while the overall moisture conservation effect was prominent instead.Under the influence of soil evaporation stage characteristics and mulching patterns,the supply of underlying net radiation flux mainly limited the first evaporation stage.In the second and third evaporation stages of evaporation,the role of sand layer structure came to the fore,and the regulating function of soil hydraulic properties gradually prevailed.In summary,the deterioration of sand layer structure would accelerate the soil evaporation process and intensify the ineffective water loss of farmland.When the mixing volume ration of sand was less than 0.5,the effect of evaporation and soil moisture retention would gradually lose,which has practical significance for revealing the degradation mechanism of gravel-sand mulched fields and its sustainable and healthy development in Northwest arid region.