The high elastic modulus of scaffolds or implants will result in stress shielding effect, which may lead to bone resorption and scaffold or implant loosening in the late stage. Porous scaffolds and implants can adjust their porosity and elastic modulus according to the mechanical environment, thereby reducing stress shielding; meanwhile, porous structures are beneficial to bone tissue growth, which is conducive to osseointegration. Three kinds of basic structure for porous scaffolds and implants by 3D printing were summarized, namely, uniform porous structure, bone-like trabecular structure and functionally graded structure. The design methods of these structures were introduced respectively, including computer-aided design (CAD)-based, implicit surface-based, image-based and topology optimization-based design method, so as to provide references for solving the stress shielding problem, as well as designing porous scaffolds and implants.