Magnesium-based alloys have a great potential to become orthopedic degradable materials for internal fixation implants, and magnesium-based implants have been shown to influence the surrounding bone structure. To understand the effects of magnesium-based implants on bone healing and remodeling, we investigated the effects of the extracts of pure magnesium and three magnesium alloys on the proliferation and differentiation of osteogenic precursor cells in vitro. MC3T3-E1 cells were selected as the study objects. Cell culture medium was used to extract the aforementioned metal materials, and the degradation products and extracts were subjected to a compositional analysis. Subsequently, the extracts were diluted to different concentrations for cell proliferation/differentiation cultures. The MC3T3-E1 proliferation and differentiation were evaluated based on the cell viability, alkaline phosphatase activity, total protein content, and cellular ability to form calcified nodules in the extracellular matrix.The magnesium ions enhanced and opposed cell proliferation and differentiation in a concentration-dependent manner. Higher concentrations of metal extracts that degraded faster (indicating higher levels of Mg ions) had an adverse effect on cell proliferation, and extracts with a lower concentration or slower degradation promoted cell proliferation. When slightly elevated, the Mg ions in the extracts suppressed the osteogenic differentiation and extracellular matrix mineralization of the cells, while they promoted these processes when present beyond a certain concentration. In cases of similar Mg ion contents, the extracts that contained Zn ions were better in promoting cell proliferation and extracellular matrix mineralization.