Abstract: Add aqueous boric acid to the aqueous blended solution of sericin and PVA,and sericin /PVA membrane was prepared by level glass plate process.The effect of boric acid on the mechanical property and insolubility property of the sericin / PVA membrane was researched.Preliminary study of the modification mechanism thermal stability of the membrane was performed by using fourier transform infrared spectrophotometry-attenuated total reflectance(FTIR-ATR) and differential scanning calorimetry(DSC).The results indicated that boric acid improves the tensile strength and insolubility property of the membrane,has positive effect on the fixing sericin protein to the membrane,and enhances its thermal stability remarkably.When the mass ratio of sericin and PVA is 3∶7 and the amount of boric acid is 0.4% of the total mass of sericin and PVA,the prepared sericin /PVA membrane has better properties.