Abstract: This paper aims to perfect the overall stability of grillage flexible supporting structure with prestressed anchors. According to the actuality, the stability analysis and design of the structure have not considered rainfall infiltration effect. Using the GeoStudio software, the overall stability parameters is analyzed for the grillage flexible supporting structure with prestressed anchors under the heavy rainfall conditions in loess area. It considers the soil moisture content influence of the ultimate uplift capacity of friction type grouting anchor. The result shows the following aspects. The rainfall duration, rainfall intensity and underground water level have obvious influence on the frame prestressed anchor flexible retaining structure. The influence of permeability anisotropy can be ignored. The safety factor of frame prestressed anchor flexible retaining structure under the condition of rainfall has lag effect. The greater the rainfall duration and saturated permeability coefficient are, the weaker the lag effect is. The greater the rainfall intensity and the higher the initial groundwater level are, the greater the lag effect is. The results of this study can be used as the guidance of the design and construction of grillage flexible supporting structure with prestressed anchors considering the influence of rainfall in unsaturated loess area.