The collagen from cattle skin has been extracted by using the pepsin, the composition of cattle skin was also analyzed. Effects of enzyme addition, temperature and extract time as well as solid-liquor ratio on extraction efficiency of collagen were investigated in this paper．The optimal processing conditions were obtained by orthogonal experiments as follows: 0.5 mol／L acetic acid as extraction solvent, the added pepsin dosage of 3000 U/g and the ratio of material to liquor 1：30, extraction at 35℃ for 8 h, the recovery yield of the collagens was 61.7%. The maximum absorb wavelength of sample is 232nm by UV scan, which is consistent with the Sigma product.