Objective: A new type of natural food preservative with pork liver as the main raw material was developed. Methods: Water-soluble porcine liver protein (WSLP), salt-soluble porcine liver protein (SSLP) and chitosan (CS) were combined to create edible composite membranes. The edible membrane components were then examined from a variety of perspectives using mechanical properties, Fourier transform infrared spectroscopy (FT-IR) and microstructure analysis. Utilized to preserve pork, and by contrasting the changes in the physical and chemical indices during the chilling process, the freshness retention capabilities of the composite film were investigated. Results: With the addition of WSLP and SSLP, the mechanical properties of edible film showed a trend of increasing firstly and then decreasing. The film was best when the amount was 40%, its film thickness was (0.267±0.001 43) and (0.264±0.001 21) mm, the tensile strength was (9.63±0.29) and (4.43±0.37) MPa, and the elongation at break was (58.37±0.90)% and (28.24±0.63)%, respectively, which were significantly different from CS film (P<0.05), and the FT-IR results showed that it was 40% WSLP and SSLP maximize cross-linking between membrane matrices. The results of scanning electron microscopy showed that the surface of the composite film prepared by 40% WSLP and SSLP was smooth and flat, and the microstructure was the best. After refrigerating pork for 12 days; It was found that 40% SSLP composite film had the best preservation performance, and the pH, total number of colonies, TVB-N value and TBARS value were the smallest in the four groups under different treatments. Conclusion: The composite membranes prepared by 40% WSLP and SSLP have the best performance.