Abstract: A method for preparing the road load spectrum of the vehicle suspension parts under multiple working conditions was proposed, and the transformation relationship between the bushing load and the load of the ball pin was studied. Based on the experimental test, the load spectrum of the ball pin road was measured, and the random load spectrum was processed with rain flow counting method. The composite probability density function of the load amplitude under multiple working conditions was established by using the mathematical statistics method, and the programmed load spectrum of a complete cycle was compiled. The load spectrum of the ball pin was converted into the bushing load spectrum by using nonlinear equation. The preparation and transformation of the load spectrum of multiple working conditions for vehicle suspension parts are realized. The method can provide reference for fatigue life prediction and fatigue life test of specimen based on test load.