In order to determine reasonable grouting parameters, control surface settlement, and reduce the risk of excessive surface settlement caused by irrational synchronous grouting parameters, this study studied the shield tunnel project between maglev T2 station and maglev T3 station. A numerical simulation method was adopted to study the influence of grouting pressure, grouting volume, and the elastic modulus of slurry on surface deformation. The results show that the tunnel synchronous grouting has a significant effect on surface settlement control. A greater grouting pressure, equivalent grouting layer thickness, and elastic modulus of slurry mean a smaller surface settlement. As the three parameters increase, the variation range of surface settlement decreases and gradually stabilizes, indicating that the grouting effect tends to saturate. By considering both grouting effectiveness and economic efficiency, it is recommended to adopt a grouting pressure of 200?250 kPa, a grouting volume of 5.4 m³ per ring, and an elastic modulus of slurry between 200 and 250 MPa. The on-site application has verified the rationality of this parameter combination. The research provides a reference for grouting reinforcement in similar shield tunnel projects.