Abstract: In this paper, the mechanism between multifunctional organic tanning agent DC and collagen was studied in a simulated approach. The white hide powder which removed the aminate, carboxylate, guanidine and hydrogen bonds was used to simulate collagen.According to the combined amount of tanning agent, the binding rate and DSC curve, it was found that amino groups performed most perfectly in the tanning process of DC, followed by carboxyl groups, whereas guanidyl group and hydrogen bonds played the least important role on the tanning process.