A method using polyethylene glycol to prepare fibroin nano/microspheres. A fibroin solution having a mass percentage of 1-30% and a polyethylene glycol solution having a mass percentage of 10-60% are first placed in a 4-60° C. environment for 30 minutes, the fibroin protein solution and the polyethylene glycol solution are then mixed, and fibroin nano/microspheres are produced via incubation and centrifugal washing.
