The invention relates to a degradable implant material of a mesoporous calcium silicate coating on the surface of a medical magnesium alloy and a preparation method thereof. The preparation process mainly comprises the steps of surface treatment of the magnesium alloy, preparation of a pecursor solution through a sol-gel method and preparation of the mesoporous calcium silicate coating through a dip-coating method in combination with high-temperature calcination. The composite coating material prepared through the method combines advantages of the magnesium alloy and the mesoporous calcium silicate material, and a magnesium alloy base body enables the composite coating to have excellent mechanical properties; the mesoporous calcium silicate coating material improves the corrosion resistance and degradation performance of the magnesium alloy; introduction of ethyl cellulose improves the material bonding strength between the coating and the base body, and the coating is distributed more uniformly; besides, magnesium ions can stimulate generation of calluses and facilitate bone healing.