Abstract: In view of the poor ditching conditions and difficult ditching of forest land, a ditching knife was designed, and the cutting soil and parameter optimization of the designed ditching knife were carried out. The finite element model of trench cutter-soil cutting was established by LS-DYNA, and the variation laws of equivalent stress, cutting resistance and cutting energy consumption in the soil cutting process of trench cutter were obtained. Taking the average cutting resistance as the index, the orthogonal simulation experiment was established to explore the influence of blade thickness, blade angle and blade cutting speed on the average cutting resistance. The orthogonal simulation results showed that the optimal parameter combination with the minimum average cutting resistance was blade thickness of 6 mm, blade inclination angle of 45°, and blade cutting speed of 2 m/s. The order of factors affecting the average cutting resistance was blade cutting speed ＞ blade thickness ＞ blade inclination. The static analysis of the optimized trench cutter showed that the strength and stiffness of the cutter met the requirements. The average cutting resistance of the ditching cutter in the forest land test is 232.6 N, and the error between the test value and the simulation value is 7.1%, indicating that the ditching cutter-soil cutting model can be used to optimize the ditching cutter parameters.