Hus1 is an important and controversial protein in checkpoint pathway. In order to know more about function of Hus1, Hus1 fragment (Hus1f, 606��846 bp) was amplified from total RNA of NIH3T3 cells by using RT-PCR, and Hus1f gene was expressed in soluble form in E.coli. The protein was purified by Ni-NTA chelating column. Polyclonal antibody was prepared by immunizing mice using purified protein, the titer of antiserum generated was 1��6400 by ELISA. Western blot analysis showed that this antibody could bind with Hus1 protein specifically, and the interaction between Hus1 and Chk1 in vivo was found by immunoprecipitation. It is useful for studying on the signal transduction pathway.