The shield machine’s ability to simultaneously cut soft soil and hard rock makes it widely used in subway tunnels, diversion tunnels and other underground engineering constructions. As the core component of the composite shield machine, the shield cutter head has a decisive effect on the work efficiency of the shield machine. When the cutter head of the shield machine is working, the positive pressure of the cutter head directly affects the working performance of the shield machine. However, when the shield machine is working, the positive pressure of its cutter head has been influenced by many factors. Therefore, the problems of evaluating positive pressure of shield machine cutter head and optimizing structure of machine cutter heat are needed. In this study, the force balance equation has been used to derive the calculation formula of the positive pressure of the soil on the cutter head. This formula can analyze the positive pressure value of the cutter head under various working conditions under different friction coefficients. At the same time, this research uses Hypermesh software to integrate the cutter head body and the force transmission ring, and uses ANSYS statics simulation analysis method to perform mechanical calculations on the shield machine cutter head. The analysis of the cutter head is 1/6, 1/3, and 1/2 effect of soil on the cutter head when the rotor is locked, and the overall stress distribution of the cutter head is analyzed to optimize the structure design of the cutter head.