Abstract: In this thesis, we propose to establish a phage display method for screening adalimumab (ADM)-specific binding peptide to provide a particular element of recognition for clinical studies of ADM, and to successfully establish an indirect enzyme-linked immunosorbent assay (i-ELISA) based on this peptide for clinical detection of ADM. With ADM as the target molecule, five rounds of peptide elution were performed using phage display technology by putting it into the M13 linear dodecapeptide library. By measuring the titer of each round of eluate, it was found that the recovery rate increased from 7.28×10^-6 to 1.55×10^-3, indicating that the peptides binding to ADM in the eluate were continuously enriched, and the enrichment effect was better; the fifth round of screening amplicons were sequenced, and it was found that five peptide sequences appeared with high frequency, which were considered to be potentially able to bind specifically to ADM and were synthesised; the specific binding ability of the five peptide sequences to ADM was verified and identified by surface plasmon resonance (SPR) and ELISA experiments, respectively, and the results showed that the first peptide sequence (Pep1) and the second peptide sequence (Pep2) showed specific binding to ADM, with the affinity constants (K_D) of 7.91×10^-5 mol·L^-1 and 1.67×10^-5 mol·L^-1, respectively, and of which the affinity constant of Pep1 with ADM isotype antibody IgG was 1.35×10^-4 mol·L^-1, which was one order of magnitude lower than that with ADM, and thus Pep1 was determined to be a specific binding peptide for ADM. Based on Pep1, an indirect ELISA method for the analysis of the antibody-drug ADM was successfully established. With the increasing concentration of ADM the OD₄₅₀ value showed a regular change, and the method can be used for clinical ADM blood concentration monitoring. In this study, we obtained a peptide that can specifically bind to ADM, and this peptide sequence can be used as a specific recognition element for ADM, which not only enables the monitoring of ADM blood concentration, but also provides an effective tool for the accurate qualitative and quantitative quantification of ADM in vivo and ex vivo, and at the same time provides a new strategy and idea for the discovery of recognition elements of other monoclonal antibody drugs.