The invention discloses a high-sealing-performance medicinal synthetic-polyisoprene pad. The high-sealing-performance medicinal synthetic-polyisoprene pad comprises, by weight, 100 parts of basic rubber, 2.5-3.5 parts of vulcanizing agent, 0.5-0.8 part of vulcanization accelerator, 3-5 parts of activating agent and 6-15 parts of filling agent. A preparation method of the high-sealing-performance medicinal synthetic-polyisoprene pad includes the steps of firstly, mixing the rubber materials; secondly, discharging a pad material; thirdly, vulcanizing; fourthly, punching; fifthly, performing alkaline extraction; sixthly, pickling; seventhly, performing fine cleaning; eighthly, silicifying. The high-sealing-performance medicinal synthetic-polyisoprene pad and the preparation method thereof have the advantages that the vulcanizing agent and the vulcanization accelerator used by the method are nontoxic, applicable to the medical field and high in safety, and the high-sealing-performance medicinal synthetic-polyisoprene pad is fast in vulcanizing, high in crosslinking degree, good in elasticity and excellent in sealing performance; when 100ml of medicine is respectively added into soft infusion bags (2000 bags) and vertical polypropylene infusion bags (2000 bags), no liquid seeps from medicine adding holes, and sealing requirements in clinical use can be satisfied.