Abstract: This study is to investigate the influence of slurry viscosity on the diffusion and filling of slurry during grouting reinforcement. Firstly, based on the newly developed test device, the diffusion process of three kinds of viscosity slurry in the aquifer of confined aquifer was simulated, and the law of slurry diffusion and filling was summarized. Fluent was adopted to simulate the grouting process. The stress distribution and variation law during the filling process of different viscosity slurries was obtained, the abnormal phenomena appearing in the physical test process was explained, and the elastic modulus of the rock mass after different viscosity slurry transformation by ultrasonic measurement was obtained. The results show that: In the process of high-viscosity slurrygouting, the formation of high-stressed cracks in the region is irregularly developed, and the slurry diffusion is deflected to the right; Under the same stress, the elastic modulus(λ)of the rock block is proportional to the viscosity of the slurry(μ_e), and the λ_max=108.07 % (μ_e=16.67)in the experiment; The medium viscosity slurry has a good transformation effect, and the area of the non-complete filling area is 23.35 %, and no abnormal phenomenon such as slurry accumulation occurs.