Porous NiTi alloys offer osseointegration and an elastic modulus similar to that of bone, which helps avoid stress shielding. However, the increase of porosity will cause the precipitation of nickel ions, which poses a safety risk. Additionally, NiTi alloys lack intrinsic antibacterial properties. In this research, functional-structural integrated Ti-5Ag/NiTi gradient alloys are prepared by SPS without adding any binder. The effects of outer porosity on mechanical property, cell compatibility, and antibacterial property of Ti-5Ag/NiTi gradient alloys were thoroughly evaluated. The results show that a clear transition layer forms at the interface between inner and outer layers, effectively inhibiting outward release of Ni ions. The increase of outer porosity can increase the number of large pores, decrease that of small pores, and enhance the connectivity between pores. The inclusion of Ag in porous outer layer grants the gradient alloy excellent antibacterial property. With the increase of outer porosity, cell compatibility, and antibacterial property of gradient alloys were improved to a certain extent. The gradient alloys can play an antibacterial role by promoting bacteria to produce ROS. Therefore, mechanical property, cell compatibility, and antibacterial property of gradient alloys can be effectively controlled by the reasonable design of the outer layer porosity, enabling the development of Ti-5Ag/NiTi gradient alloys with balanced mechanical property and antibacterial property for orthopedic implants.