As the current situation that the research of pre-cutting method in China lack relevant fundamental theory and design method

based on the soil mechanics and the mechanical design method of tunnel shield

a set of design method of the pre-cutting method was put forward.Using the modular decomposition method

the function and key technology of 9 sub-structure of the pre-cutting method was analyzed.The pushing force that is needed for the chain saw to cut into the section of the tunnel and the cutting torque of the chain saw was calculated due to the similarity principles of the cutting.And the design of the model of the pre-cutting method machine was finished according to the specific geologic parameter of Beijing.The results of the model summarize the relevant key technology and provide basic theory and design reference for the future development of the pre-cutting method.