Abstract: Aiming at optimizing the vibration characteristics of the tractor frame and improve driving comfort, vibration of the tractor frame based on the modal programming method was analyzed and optimized in this paper. The time-domain vibration parameters in the X, Y, and Z directions of the tractor frame were tested, and the linear self-power spectrum parameters were calculated by using the Fourier analysis method. Acceleration peak values occurred at 8.125 Hz, 21.25 Hz, 42.5 Hz, and 85.625 Hz. The finite element model was established and modal parameters were solved. The results show that the difference between the second-order natural frequency, the fourth-order natural frequency, and the vibration excitation peak frequency was less than 3 Hz. The frame modal parameters were optimized based on modal programming method and response surface method. The influence law of each factor on the target parameters was determined. The second and fourth order modal frequencies were optimal when factors A, B, and C were 149.90 mm, 5.01 mm, and 65.00 mm, respectively. The simulation results showed that the optimizing natural frequencies of second and fourth order were 48.53 Hz and 89.97 Hz and the corresponding error rates were 1.99% and 1.03%. The analysis methods and conclusions in this paper may be extended to the vibration optimization of other agricultural machinery.