The accuracy of digging resistance calculation is the basis of excavator simulation research. The traditional digging force model does not consider the existence of resistance moment. Taking a domestic 365T hydraulic excavator as the research object, the range of resistance coefficient needed for the extreme digging force was determined through experimental test. Based on the measured digging resistance and the measured stress, the corresponding poses of the five largest digging force points on the synthesis digging trajectory were selected. Through simulation study, the extreme digging force and the traditional digging force model were used respectively to compare the stress and displacement of the five digging poses and compared with the measured maximum stress value. It is verified that the extreme digging force model has higher safety and reliability.