Abstract: The surface morphology and thermal stability of leather scraps were significantly changed by using sodium oxalate to remove chromium 94.9%.The hydrolysate of collagen was further prepared by hydrothermal treatment of dechromed leather scraps.The results showed that the collagen hydrolysate with a heavy average molecular weight M_w=2.86×10⁵ g/mol, an ash content of 0.530% and a chromium content of 944 mg/kg was obtained by reacting the dechromated leather scraps at a solid content of 10% and a temperature of 110 ℃ for 7 h in a hydrothermal reactor.It can be seen that the combination of chromium leaching by sodium oxalate and hydrothermal method can obtain collagen hydrolysate with high molecular weight and low ash content,which can provide a novel way to resource the chromium leather scraps.