Silk fibroin (SF) powder was prepared by a nontoxic low-sodium system to avoid introducing massive unwanted chemicals during the SF hydrolysis process. In this study, water-soluble and water-insoluble SF powder, were obtained through lyophilised SF solution by boiling degummed silk fiber in low-concentration Na2CO3 solution with a certain degree of pressure. Compared with traditional SF hydrolysis systems, this study provides a simple and potentially time-saving approach to produce SF powder at a low cost.