Objective:To single amino acid mutation of the full human scFvs against TSLP to enhance its affinity.Methods: The specific scFvs against TSLP was screened in our previous study and here the three-dimensional structures of TSLP and anti-TSLP scFvs were simulated by Discovery Studio system,then the molecular docking was made.The amino acids of binding epitope were randomly mutated and the mutated amino acids were selected which could remarkably improve the affinity of scFvs.The primers were designed based on the sequence of mutation amino acids and the scFv sequences were mutated by the overlapping extension PCR.The DNA of mutated scFvs was ligated with the expression vector pLZ16 and transformed into E.coli DH5αF′.Then the scFvs were expressed and the scFvs with improved affinity were selected by ELISA and BIAcore.Results: The five scFvs with single amino acid mutation were screened out by DS system,which could elevate the affinity of scFvs.The mutated anti-TSLP-scFvs were amplified by PCR,which size was about 1 000 bp.The mutated scFvs with correct sequence were expressed,and the mutated scFvs with improved affinity were detected by ELISA and BIAcore.The affinity of selected mutated scFv (M4) has been about 10 times higher than the scFv nonmutation.Conclusion: The affinity of anti-TSLP-scFv has been improved successfully.