Abstract: With the rapid development of 3D printing (Additive Manufacturing) and the urgent demand of aerospace for lightweight structure, porous structure, especially periodic lattice structure, has attracted more and more attention. In view of the fact that 3D printing technology is not mature enough and the printed lattice structure inevitably has defects, therefore, it is necessary to evaluate the performance of lattice structure with defects. Firstly, the influence of the missing of the strut in different positions on the mechanical properties of the structure is carried out. The experimental and finite element results show that the mechanical properties of the structure decrease most when a strut is missing in the center. Furthermore, the relationship between the number of missing members in the center and the mechanical properties of the structure is established. The results can provide guidance for the application of lattice structure in practical engineering structure.