The present application belongs to the technical field of polymer materials, and hyperbranched polylysine powder with a low polydispersity index and a production method thereof provided. The present application adopts a thermal initiation polymerization method, Compared with the traditional method, the production method of hyperbranched polylysine has the advantages of no additional steps of introducing and removing amino protecting groups, no need of activating carboxyl groups, easy purification of products, short production period, controllable molecular weight of products and low polydispersity index (1.01-1.2), and is suitable for industrial production of hyperbranched polylysine materials, especially medical-grade hyperbranched polylysine materials.