The development of intelligent agricultural machinery needs rich technical reserves. In order to inquire the fatigue life of frame of the combined corn harvesting locomotive, the fatigue characteristics of the corn harvesting locomotive frame under complex working conditions are analyzed based on the measured load characteristics. Through theoretical and simulation analysis, and full consideration of practical experience to determine the measurement point, and complete the signal analysis after the collection of payload signal. Based on the finite element method, the related characteristics of the frame are analyzed, and the random vibration analysis is completed by using the measured load. The stress power spectrum of the dangerous node is obtained, and the fatigue life of the frame is analyzed in time domain and frequency domain by combining the S-N curve of material and the principle of fatigue cumulative damage. The maximum stress power spectrum curve and the measured stress power spectrum at different speeds are obtained by random vibration analysis, and the life of the dangerous parts of the frame is calculated based on Drilik"s empirical formula. Results show that the fatigue weak position are in the junction among the longitudinal beams, the junction between bridge bearings and frame, and the junction between rear axle and rear frame, which fatigue life are in commonly 10⁶. The life of other positions of the frame is in more than 10⁷. The speed increase will reduce the fatigue life of the frame. These provide the reference for the design of the frame and optimization.