Polylactic acid (PLA)-based composite reinforced with magnesium alloy wires (Mg wires) is prepared by lamina stack method for orthopedic implants. The impact behaviors of the composite are experimentally and theoretically studied. The results suggest that Mg wires could significantly improve the impact performances of PLA. The initial impact strength of the composite with 10 vol% Mg wires is about 5 times that of pure PLA. After 3 weeks, immersion at 50 degrees C, the impact strength of the composite at 10 vol% could retain to be 10 kJ/m(2), while pure PLA losses its impact strength. Further theoretical studies by finite element method indicate a small diameter for the wires could significantly improve the impact properties of the composite and promote the energy absorption of the wire components. Moreover, increasing the lamina numbers could also improve the impact properties of the composite.