Abstract: To investigate the influences of basalt fiber reinforced polymer (BFRP) grid and steel fibers on the mechanical properties of magnesium phosphate cement mortar (MPCM), BFRP grid reinforced MPCM composite (GRMM) was prepared. The effects of material forms (steel fiber reinforced, BFRP grid reinforced and composite reinforced), BFRP grid thicknesses (1 mm, 2 mm and 3 mm), and BFRP grid surface forms (untreated and sand-sticked) on the tensile stress-strain curves, bending stress-deflection curves, and key indexes of GRMM were investigated by the axial tensile test and four-point bending test. Moreover, the roles of steel fibers and BFRP grid in GRMM were also studied. The results show that steel fibers mainly play a role in the early stage, which can effectively inhibit the generation of cracks and improve the strength and toughness of GRMM. The incorporation of steel fibers increases the tensile and bending capacity by 24.23% and 215.33%, respectively, and improves the crack resistance, ductility and energy consumption of both types of specimens. The tensile stress is the mainly borne by BFRP grid, which plays a role throughout the whole loading process of GRMM. The incorporation of the BFRP grid improves the peak deformation of both tests by more than 70 times, but the BFRP grid is not coordinated with the MPCM in the specimen. Combined with the strengthening effects of steel fibers on the matrix and the good deformation of BFRP grid, the cracking resistance, strength, ductility and energy dissipation capacity of MPCM matrix are improved. As the thickness of the BFRP grid increases, the strength and energy dissipation capacity of the GRMM specimens are further improved. Sticking sand on the BRFP grid does not significantly affect the mechanical properties of GRMM.