To explore biodegradable intravascular stents, Mg-3Zn-0.8Zr-1HA composite (mass fraction, similarly hereinafter) and Mg-3Zn-0.8Zr alloy were prepared to investigate the effects of nanohydroxyapatite (n-HA) on the mechanical and biodegradable properties of Mg-3Zn-0.8Zr alloy. Results indicate that the n-HA particles are distributed uniformly in the matrix, so the grains of the matrix are refined, and the ultimate tensile strength and elongation are increased. The immersion tests in the simulated body fluid (SBF) show that the surface morphologies of the two kinds of materials are quite different as the immersion time is prolonged. After immersion for 20 d, the surface of the composite with n-HA is still perfect and covered with Ca and P, while a lot of pitting occurs on the surface of Mg-3Zn-0.8Zr alloy. The electrical current densities of the composite and the alloy are 0.701×10-5 A·cm-2 and 1.034×10-5 A·cm-2 respectively, which demonstrates that the corrosion resistance of the Mg alloy is significantly improved by the addition of nanohydroxyapatite powders.