In this paper, magnesium oxide (MgO) and potassium dihydrogen phosphate (KH2PO4) were used as the solid phase components of magnesium phosphate bone cement, and different content of phytic acid modified hydroxyapatite (IP6-HA) powder was introduced to prepare various magnesium phosphate composite bone cement with different magnesium and phosphorus ratio (M∶P). By adjusting the ratio of MgO and KH2PO4 in magnesium phosphate powder and the content of IP6-HA, the mechanical properties and curing time of bone cement were improved, and the curing mechanism of bone cement was studied. The results show that when the ratio of magnesium to phosphorus is 4 and the content of IP6-HA in the solid phase is 5% (mass fraction), the growth effect of struvite crystals (MgKPO4·6H2O) is the best, the curing time is 7.5 min, the compressive strength can reach 49 MPa, and the strength can reach 69.3 MPa after curing for four weeks. The IP6-HA modified magnesium phosphate composite bone cement obtained from the experiment has good mechanical properties and suitable curing time, which has potential biomedical application prospects.