Objective To analyze the epitopes of anti-hepatitis C virus(HCV)antibodies by peptide library biopanning. Methods Phage random peptide library of 12 amino acids was immunoscreened with purified IgG from the sera of hepatitis C patients. Positive clones which were obtained after 3 rounds of biopanning were detected by ELISA and 4 of them were sequenced. Results After 3 rounds of screening, the radio of output to input increased from (4.6×10~(-4))% to (5.3×10~(-2))%, meaning the enrichment was effective. At the third round of screening, all the selected clones proved to specifically react with the sera for immunoscreening. Four positive phage clones were sequenced, which shared a very conservative sequence and was named as C1. Its inserting sequence in the coat protein III was deduced to be GSMSPYVRWYTP, and the positive rate of C1 reacted with 20 cases of HCV patients was 85%.Conclusion The antigen-mimic peptide C1 is successfully screened from 12 random phage peptide library and it has some diagnostic value.