Abstract: The strength analysis and fatigue analysis are performed by using Pro/E and Pro/M on the base of material analysis, mechanical performance test and loading analysis. The authors confirm that breaking mechanism of spline shaft is fatigue breaking, and put forward corresponding measures to solve the problem from the aspects of designing, material choosing, manufacturing, and controlling quality etc，it is recognized in manufacturing spline shaft, 50CrMoA should be chosen and tempered with the addition of surface hardening, and S, P, Cu content in steel should be controlled, the diameter of spline shaft and the tooth root radius should be increased to increase the reliability and life of the spline shaft.
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Key words: high pressure pump, spline shaft, loading analysis, strength analysis, fatigue analysis