By exploring the out-of-plane wrinkles and delamination defects easily generated during the autoclave forming process, out-of-plane wrinkle test pieces with different sizes and wrinkle layers and delamination test pieces with various sizes are prepared. Tensile, compression, short beam shear and three-point bending tests are carried out on the test pieces. Then the failure morphologies of the test pieces under test are compared and analyzed to explore the effects of outof-plane wrinkles and delamination on the comprehensive mechanical properties of the composites and failure mechanism. The results show that the tensile strength, compressive strength, interlaminar shear strength and flexural strength of the composites with out-of-plane wrinkles respectively decline by 47%, 77%, 23% and 49%, and the number of wrinkled layers of out-of-plane wrinkles has a more significant effect on the mechanical properties than the size; delamination can cause a significant decrease in the compressive strength, interlaminar shear strength and flexural strength of the composites which respectively decline by 24%, 38% and 15%, while it has little effect on the tensile strength.