Abstract: Objective To study the property and function of p57 protein, finding the plasma membrane binding sites of p57. Methods The distributions of the wild-type p57 and its mutants in cells were observed by fluorescence microscopy. The blowing crack technology was used to detect the binding between the wild-type p57 and its mutants with plasma membrane. Differential centrifugation technology was used to prepare subcellular components and the contents of p57 in subcellular components were detected by Western blot. Results It was found that the fragment 386-461 of p57 has a similar distribution in cells and similar plasma membrane binding abilility as the intact protein, but the fragment 1-299 or 1-432 hasn’t. Overexpression of the fragment 386-461 can compete the membrane binding site with the intact p57. Conclusion The C-terminal domain containing the fragment 386-461 is responsible for the binding of p57 to plasma membrane.