Enterovirus 71 (EV71) is a member of the Entero-virus genus of the Picaviridae family and is the major cause of Hand,foot,and mouth disease (HFMD) in children.Different strains from Gansu were cloned and the P1 protein was sequenced and analysed.Results indicate that there are three kinds of EV71 infections prevalent in Gansu.The VP1 protein from one of these strains,55F,was expressed.The recombinant protein was expressed with high level and reacted specifically with the EV71 patient antibody,the recombinant protein was also applied to raise antiserum in rabbits and after the fourth injection a high titer of antiserum was detected by ELISA assay.These data are useful for further clarification of prevalent EV71 strains in the north of China at the molecular level and provide a basis for EV71 diagnosis.