The invention discloses a preparation method of sericin hydrogel, the method is as follows: first, weighting domestic silkworm fibroin deletion form mutation variety silkworm cocoon for LiBr or LiCl extraction and dialysis and purification to obtain a non-degradable sericin water solution with a mass percentage concentration of 0.1-4%; concentrating the sericin water solution to 1.5-10%, adding a cross-linking agent to the concentrated sericin water solution (wherein 2-500muL of the cross-linking agent is added into each L of the sericin water solution), fully mixing, and placing at 4-45 DEG C for 5 seconds to 36 hours to obtain the sericin hydrogel. The sericin hydrogel has biological activity and multiple functions, can be used as carrying growth factors, drugs and cell carriers treatment, and can be applied in repair of a variety of soft tissue injuries, including but not limited to skin damages, muscle damages, injuries of blood vessel, nerve injuries, myocardial damages, and the like, and treatment of diseases.