This paper reported the preparation of type II collagen from chick sternal cartilage.Pepsin was applied to digest the telopeptide of type II collagen,and the effect of time,temperature and pepsin concentration on the secondary structure of type II collagen were researched using circular dichroism.Atomic Force Microscope and FT-IR were applied to identify the structure of type II collagen.The results suggest that time and temperature cause significant impact on the secondary structure of type II collagen.Type II collagen of higher extraction rate and better stability were obtained with the extraction time of 32h and 1% pepsin concentration at 37℃.