The shield tail synchronous grouting area is located behind the tunnel segment wall. Due to its closed space, it is difficult to visually observe the diffusion of slurry, resulting in the unclear distribution characteristics of synchronous grouting materials. Therefore, a shield tail synchronous grouting simulation device is developed to study the pressure change and upper soil settlement in the process of synchronous grouting. The results show that the soil pressure on the upper part of the moving axis of the slurry outlet increases gradually under the influence of grouting pressure, and decreases gradually with the distance from the slurry outlet, and the pressure on both sides increases gradually, resulting in obvious soil arching effect; The top pressure of the stabilized soil box, i.e. the internal pressure of the slurry, is determined by the upper load and has no direct connection with the grouting pressure; The surface settlement caused by grouting process is mainly determined by grouting pressure, followed by the influence of slurry properties; The thickness of the solidified grouting body is small in the transverse direction near the slurry outlet, relatively large on both sides, and the thickness distribution is relatively uniform in the longitudinal direction.