Aiming at the problems of softening, expansion and instability of weakly cemented soft rock surrounding rock in water-bearing environment in western mining area, combined with FLAC3D numerical simulation, a fluid-solid coupling model was constructed to analyze the mechanical properties evolution and instability mechanism of surrounding rock under water-rock interaction. Through rock mechanics experiments under different water contents, the strength weakening law was obtained and the weakening function was established, and then the expression of elastic-plastic stress distribution and loose circle radius was derived. Combined with the geological parameters of Selian No.2 Mine No.12507 Face, a design scheme of bolt-mesh-cable cooperative support based on the classification of medium loose circle was proposed, and numerical simulation was carried out to verify its adaptability. The results showed that the increase of water content significantly aggravated the deformation of surrounding rock and expanded the range of loose circle. The designed support scheme could effectively control the deformation of surrounding rock and ensure the stability of roadway. The research results provided theoretical basis and engineering guidance for roadway support under similar conditions.