The performance of the new generation aero-engine is strongly dependent on the application of integral blisk technologies, while the high-risk failure of integral disk joints severely restricts the promotion of those technologies. Therefore, the molecular dynamics method is used to investigate the influence of nanopores on the tensile properties of single crystal/polycrystalline Ni composites. The results show that the addition of single crystal nickel can increase the tensile strength of single crystal/polycrystalline Ni compared with polycrystalline nickel. The influence of pore position distribution on the tensile properties of single crystal/polycrystalline Ni is investigated. The simulation results show that nanopore defects in a single crystal region significantly aggravate the fracture at the single crystal/polycrystalline Ni interface. Pores not only penetrate the interface of composites but also rapidly expand inside the single crystal and the polycrystalline crystal, in which the interface of composites is further reduced resulting in the failure acceleration of single crystal/polycrystalline Ni composites. On the contrary, when the pores are in a polycrystalline region, the interface of single crystal/polycrystalline Ni hinders the amorphization of the polycrystalline nickel side and inhibits the pores from spreading toward the interface. When the pores are in the interface region, the pores do not continue to expand into the single crystal, but propagate inside the polycrystalline crystal. The effect of the porosity of interface pores on the tensile properties of single crystal/polycrystalline Ni is also discussed. It is found that the tensile strengthof single crystal/polycrystalline Ni decreases rapidly when the void porosity exceeds 0.8%. Finally, the influence of the number of voids on the tensile properties while maintaining the porosity of the interface pores is analyzed. When the porosity of the prefabricated pores of the interface is kept constant at 0.8%, the larger the number of pores (i.e., the smaller the pores), the larger the elastic modulus. In the plastic deformation stage, due to the large number of dispersed small pore structures at the interface of the single crystal/polycrystalline Ni composites, the dislocation motion is hindered, which plays a certain strengthening role and improves the tensile strength of the single crystal/polycrystalline Ni composites. It can be concluded that single crystal/polycrystalline Ni with dispersed small pores has better tensile properties than those with large pores.