Abstract: To reduce the ash content of bone collagen peptide and improve the quality of bone collagen peptide products. In this paper, the method of nanofiltration desalination was used to remove ash. The process parameters for nanofiltration desalination of bone collagen peptides were optimized through design response tests. The changes in physical and chemical indicators, amino acid content, molecular weight distribution, content of various elements, and sensory scores of samples treated with nanofiltration membranes were analyzed. Results showed that, the optimal desalination process conditions were sample concentration of 5%, cycle times of 7 times and pressure of 0.5 MPa. Under this condition, the desalination rate was 65.89%±1.25%. After nanofiltration membrane treatment, the quality of the sample was significantly improved, but the amino acid content did not change much. Through the measurement of molecular weight distribution, it was found that nanofiltration desalination had little impact on the change of molecular weight distribution, the components with molecular weight less than 3000 Da accounted for 97%, which was in line with the provisions of the national food safety standard GB 31645-2018 bone collagen peptides. ICP-MS was used to analyze the changes in the content of various elements before and after desalination, and it was found that the content of various elements in the sample decreased to varying degrees, the content of Na, K, P, Mg, Ca decreased significantly (P<0.05). Through sensory evaluation, it was found that the color of the samples did not change while the clarity increased, the saltiness decreased significantly, the overall acceptability increased. This study would provide technical support for the production of high-quality bone collagen peptide products.