Waterrich fractured zone always results in problems in construction. During the construction of a foundation pit of Nanjing Metro, problems, such as serious water inflow, settlement and deformation of support structure and limited grouting effect by traditional grouting materials, occur. In the paper, the water seepage of the foundation pit is analyzed by means of hydrogeology method and highintensity resistivity method. The grouting reinforcement process of the waterrich fractured zone is cosimulated by means of COMSOL numerical software, comparison and contrast is made between the water seepage pattern before grouting and that after grouting, and site grouting test is carried out. The grouting effect is testified by means of geology detection radar and packer permeability test. The results show that good grouting reinforcement effect has been achieved by using new types of accelerators, and COMSOL cosimulation method can provide guidance for grout design. 