Abstract: This paper calculates the stresses, displacements, permanent bore enlargement, excess, degrees of autofrettsge and push force in secondary mechanical autofrettage technique of thick-walled cylinders with bilinear materials. The results prove the feasibility of the secondary autofrettage technique, and the consistency between theoretical analysis and experimental results. This technique can meet the autofrettage requirements of thick-walled cylinders of different bore diameters and materials.