Biocrusts (biological soil crusts), as ubiquitous living covers on soil surface of the enclosure grassland in the frozen ground region of the Qinghai-Tibet Plateau, is one of the important factors which influenced the frozen soil environment. Based on the analysis of soil temperature and unfrozen water content of the shallow soil layer (0-50cm), the hydrothermal process of the shallow soil layer under the covering of two types of biocrusts in Maduo in the source area of the Yellow River (SAYR) were studied. Preliminary results showed that biocrusts have a significant impact on the unfrozen water content and soil temperature of the shallow soil layer. Compared with the bare soil, both types of biological crust increased the unfrozen water content of soil in different soil layers and lowered the temperature of shallow soil layer in the thawing period. While there is no significant effect on the soil unfrozen water content and temperature in the freezing period; In the thawing period, the biocrust decreased the soil unfrozen temperature in the shallow soil layer by 1.1-1.9℃, which was higher than that of the light biocrust by 0.8-1.1℃. Meanwhile, during the thawing period, the dark biocrust increased the soil water unfrozen content in the 5-15 cm soil layer by 1%-5.4%, while the light biocrust increased soil water content in 30 cm by 5%-12%, no significant effect on the 5 cm soil depth; Eventually, the hydrothermal coupling process was observed in the shallow layer of soil under biocrusts in the frozen ground region. The soil water-heat process could be divided into three stages according to the water and temperature changes: (1) when the soil temperature of soil crust was less than - 4℃, the soil unfrozen water content was maintained at 4.3%; (2) when the soil temperature increased from - 4℃ to 4℃, the soil water content would increase with the temperature increasing; (3) when the soil temperature was higher than 4℃, the soil unfrozen water content was more than 10%, the soil water content decreased with the soil temperature increasing. The results reveal the key effect of biocrusts on the hydrothermal process of frozen soil in the shallow soil layer and the study provides the theoretical basis for the ecological recovery in the frozen ground region.