In order to further study the stability of large diameter rectangular pipe jacking tunnel face, when active limit failure of large diameter rectangular pipe jacking occurred, the failure area of soil mass in front of tunnel face was simplified by establishing a practical engineering geological numerical model. Based on the failure mode, the existing wedge calculation model was improved, and the calculation method of active limit support pressure of rectangular section was deduced. The limit support force obtained by this method was compared with calculation results obtained by the actual engineering to verify the rationality, and then the sensitivity analysis of influencing factors was carried out. The results show that the proposed calculation model of trapezoidal wedge is close to the numerical simulation results, and it is better than the results calculated by equivalent section. Therefore, this study can provide help for determining the reasonable support pressure of large diameter rectangular pipe jacking in the soil.