PLA based porous composite materials oriently reinforced by ordinary Mg wires (PLA-Mg) and biomimetic-treated Mg wires (PLA-MC) were fabricated. PLA-Mg and PLA-MC both realized long-term and uniform release of Mg2+. Compared by PLA-Mg, the release of Mg2+ of PLA-MC was more uniform. The presence of Mg wires promoted the hydrolysis of PLA in PLA-Mg, which featured with crystallinity of PLA in immersed PLA-Mg reaching 0.67 with an increase of 19.6% compared with immersed PLA. Comparatively, the degradation of PLA in PLA-MC was lower and regulated, which was characterized by crystallinity reaching 0.55 with a decrease of 1.8% compared with soaked PLA. Moreover, the release of Mg2+ in PLA-Mg and PLA-MC both followed exponential rules of decline, which could be used for predicting that the final C(Mg2+) approached 41.67 and 40.83 ppm by mathematical models, respectively. More obvious cell adhesion and cell viability at interface between PLA oriented pore walls and biomimetic-treated Mg wire endowed PLA-MC with better biocompatibility than PLA-Mg or PLA, exhibiting the greatest capacity of cell adhesion and proliferation due to more stable variation in pH and the long-term smaller release of Mg2+. The results could provide references for the development of new bone repair materials.