The invention discloses a preparation method of miriplatin 
hydrate, which comprises the following steps: controlling the temperature to 40-90 DEG C, adding 
Oxaliplatin and C13H27COOM in a dissolved reaction 
solvent, and reacting for 1-6d to prepare the miriplatin 
hydrate, wherein the 
molar ratio of the 
Oxaliplatin to the C13H27COOM is 1:0.5-5, and M is 
sodium, 
potassium, 
ammonia, 
calcium or nitrogenous organic alkali. Compared with the existing preparation method of miriplatin 
hydrate, the preparation method disclosed by the invention has the outstanding advantages of environment-friendly synthesis lines, no 
silver ion residues, no toxic solvents, short lines and convenience in operation, the obtained product has good quality (
chemical purity of 99.5% and optical purity more than 99.9%), high yield (more than 92%) which is 10% higher than that of other lines and low cost, is public-benefit and environment-friendly, is easy for industrial production, has good practicability and can produce better economic and 
social benefits. In addition, the miriplatin hydrate used for injection prepared according to the preparation method of the miriplatin hydrate disclosed by the invention has low production cost and high quality, and can reduce adverse reactions and treatment cost for patients to a great extent.