Herein, we provide a novel method of using finite element analysis to guide the improvement of manufacturing processes on the basis of physicochemical analysis. First, based on the theoretical analysis of the force of the connecting rod, the solid model of cracking connecting rod is established by SolidWorks. Then the static stress analysis, modal analysis and fatigue analysis are carried out by ANSYS, determining the location where the connecting rod is prone to failure. Second, the influence of processing technology and other factors on the failure of connecting rod is analyzed, and several improved schemes for the manufacturing process are proposed. Finally, the fatigue test of the connecting rod is performed to verify the effect. Compared with the unimproved connecting rod, the tension and pressure of the improved connecting rod increased to 92.34 KN and -425.7 KN, respectively. The safety factor under this load is 1.8, which has increased by 20 % compared to 1.5 before the improvement.