Abstract: Objective 304 austenitic stainless steel mandrel manufactured by laser metal deposition is taken as an example in the paper. Fatigue gradual reliability of metal parts manufactured by laser metal deposition is analyzed. Fatigue reliability index of metal parts manufactured by laser metal deposition is compared with that of metal parts manufactured by traditional manufacturing process. Methods Based on reliability concept and strength degradation theory, P-S-N curve of the mandrel is drawn from fatigue data of smooth specimen manufactured by laser metal deposition and fatigue data of smooth specimen manufactured by traditional forging process in the literature. The mean and standard deviation of fatigue life for the mandrel under random equivalent stress are obtained by P-S-N curve and Latin sampling method. Fatigue gradual reliability of the mandrel is obtained by equivalent Weibull distribution function. Results Compared with P-S-N curves of the two kinds of mandrel, it can be seen that the mandrel manufactured by laser metal deposition has higher fatigue strength. In the initial stage, the two kinds of mandrel have similar reliability under the different applied equivalent loads. With the increase of cyclic loading times, fatigue gradual reliability of the mandrel manufactured by traditional forging process decreases rapidly due to its low fatigue strength. Conclusion The mandrel manufactured by laser metal deposition under the same working conditions has higher fatigue gradual reliability than that manufactured by traditional forging process. Laser metal deposition can effectively improve fatigue gradual reliability of metal parts.