Objective To establish a low-cost and high-sensitivity chemiluminescence immunoassay for thyroid stimulating hormone in human serum by using biotin-avidin system.Methods Two monoclonal antibodies of TSH were used in the assay. One was coated on the microtiter plate and the other was biotinylated. The streptavidin labeled horse radish peroxidase, luminol and hydrogen peroxide were used in this system to establish the assay. Results The assay sensitivity of the method was 0.01mIU/L. The intra-assay and inter-assay coefficients of variation were 2.01%-5.40% and 2.96%-17.9%, respectively. The analytical recovery was 90.6%-114.4%. The correlation coefficients were beyond 0.99 after serial dilutions of two samples with high concentration of TSH. The examination result of the assay correlates well with that of IRMA and Roche ECLIA. Conclusion The chemiluminescence immunoassay of biotin-avidin TSH established in this study is low-cost, sensitive, specific and stable. It may have a promising prospect in clinical application.