The invention relates to a magnesium alloy material for an implantable bone repair internal implant and a preparation method thereof. Magnesium powder and calcium metasilicate powder are mixed and then put into a mold, and the mass fraction of the calcium metasilicate powder in mixed powder of the magnesium powder and calcium metasilicate powder accounts for 20%; and after cold press molding under the pressure of 750-900 MPa, hot pressed sintering is conducted in the environment with the temperature being 520-600 DEG C and the pressure being 100-200 MPa, and accordingly the magnesium alloy material for the implantable bone repair internal implant can be obtained. Compared with the prior art, a certain proportion of calcium metasilicate powder is added into the magnesium powder, and thus biocompatibility and corrosion resistance of magnesium alloy are improved. The magnesium alloy material for the implantable bone repair internal implant has good biocompatibility and safety, and can be degraded directly inside the human body, and therefore pains caused by the secondary operation of patients are avoided.