Abstract: In order to further improve the transmission performance of the crawler tractor, from the perspective of promoting the rationality of the combination structure of the gearbox, the finite element analysis technology was used to carry out the design.According to the position relationship and the load bearing degree of each shafting in the gearbox of the crawler tractor, combined with the characteristics of the field working environment of the crawler tractor, the components were fully discretized, and the pressure distribution cloud of the gearbox was obtained by using ANSYS. The expected optimization goal was achieved and the performance test was carried.The results showed that the relative error between the natural frequency test value and the finite element simulation value was controlled within 7% after the local optimization of the internal composite structure of gearbox, and the vibrational mode characteristics were well displayed.The error between the test stress value and the stress value under the finite element analysis is small, which could be kept within 10% to meet the requirements of strength and rigidity. The optimization of the combined structure could effectively avoid the resonance area and stress concentration area, and would provide direction for the depth optimization of tractors and other similar agricultural power machinery structures.