The stress of human bone in daily activities is complex. To obtain the optimal porous titanium alloy structure suitable for bone implants, it is necessary to analyze the mechanical properties of porous structures. According to the compression, torsion, and bending loads of human bone, three kinds of porous structures (TO-C, TO-T, and TO-B) were designed and reconstructed by topology optimization method. The mechanical properties of different porous structures were studied by finite element simulation in compression, torsion and bending states. Finally, the compression test of porous specimens prepared by selective laser melting technique was carried out. The simulation results show that the compressive strength and bending strength of TO-B structure are optimal, while the torsional strength of TO-T structure is optimal. The compression test shows that the compressive strength of three structures at a porosity of 60% ranges from 188.35 MPa to 258.88 MPa and the elastic modulus ranges from 2.51 GPa to 4.16 GPa, all of which meet the requirements of human bones. By combining simulation and compression test to comprehensively analyze the mechanical properties of porous structures, it is found that TO-B structure has the best comprehensive performance and is the optimal type of porous structure for orthopedic implants.