Abstract: Objective To analyze genes of Fab antibodies against Clonorchis sinensis CAg.Methods DNA sequences of 2 positive antibody clones were determined.Analysis software of NCBI and Ig Blast Analysis of Immunoglobulin sequences were used to analyze their deduced amino acid sequences.Secondary structures of 2 positive clones' Fd fragment and light chain were also modeled.Results The positive clone gene of E38 and E05 were highly homologous to the variable region of human κ light chain and γ heavy chain gene.The deduced amino acid sequences both had typical characters of Ig light and heavy chains'variable regions.The second structures was modeled with analysis software.Peptide chains containingβ-sheets were found and turns formed sheet structure in the amino acid sequences of these two clones.This strucure accorded with the model of Ig secondary structure.Conclusion Both E38 and B05 positive antibody clones belonged toκchain andγchains Fd variable region of human Ig gene.