The invention relates to medicinal gelatin microspheres and a preparation method thereof, and belongs to the field of medicine preparation. The active ingredient of the medicinal gelatin microspheres is trimetazidine or a medicinal salt of the trimetazidine. The preparation of the microspheres adopts a chemical cross-linking method, and comprises steps of emulsification, deoiling and dewatering, chemical cross-linking, washing and drying, and the like. According to the preparation method, the particle size, the appearance, the encapsulation efficiency, the drug loading rate are adopted as indexes to comprehensively optimize the carrier, the oil phase, the dewatering and deoiling agent, the cross-linking curing agent, and other reagents added in the process, wherein the carrier, the oil phase, the dewatering and deoiling agent, the cross-linking curing agent, and other reagents are suitable for preparation of the microspheres of the present invention. The prepared microspheres have characteristics of smooth surface, particle size of 50-200 mum, drug loading rate of 30-35%, and has a slow release effect under the common dissolution conditions. In addition, the blood drug level of the microspheres is stable in vivo, and is better than the blood drug level of ordinary tablets.