Preparation method of medical-grade polyvinylpyrrolidone K90

The invention discloses a polyvinylpyrrolidone, namely PVP for short. The polyvinylpyrrolidone is a nonionic polymeric compound, and is the most characteristic fine chemical variety which is researched the deepest and the most widely in N-vinyl amide polymers. The polyvinylpyrrolidone belongs to the technical field of polymerization of high polymer materials, and particularly relates to a preparation method of medical-grade polyvinylpyrrolidone K90. The problems that an initiator polymerized by the existing polyvinylpyrrolidone K90 has toxicity, and is not suitable for production of the medical-grade polyvinylpyrrolidone K90 are solved. By adopting the initiator which is free of toxicity on a human body, the preparation method is simple in production process, convenient for post-treatment, nontoxic and harmless; the cost of the product is greatly reduced; and the preparation method is suitable for the production of the medical-grade polyvinylpyrrolidone K90.