Abstract: Objective: To compare the results of serum HBsAg detection by eletrochemiluminescence immunoassay(ECLIA) and enzyme-linked immunobsorbent assay(ELISA).Methods: ECLIA and one-step and two-step ELISA were used to detect quantitative HBsAg and 99 serum samples which were divided into four models:①HBsAg(+)/HBeAg(+)/HBcAb(+),②HBsAg(+)/HBeAb(+)/HBcAb(+),③HBsAg(+)/HBcAb(+),④HBeAg(+)/HBcAb(+).Results: The within-day CV by ECLIA increased 3.3% and 3.2% compared to by one-step ELISA and two-step ELISA alone;and the between-day CV by ECLIA increased 3.5% and 3.3%,and the sensitivity was 0.063,0.5 and 0.25ng/ml respectively.The positive ratio by ECLIA and one-step,two-step ELISA was 100% in model①②③.The result was positive in two samples of model④by ECLIA 1:50 dilute and two-step ELISA,while the result was negative by ECLIA undiluted and one-step ELISA.In model①,the level of 1:50 diluted HBsAg COI was higher than that of undiluted.Conclusions: One-step ELISA is simple and quick in detecting HBsAg,but too high or too low concentration of the sample may issue false negative.To avoid hook effect,two-step ELISA is recommended.ECLIA has a high sensitivity,but there also exists hook effect.Prediluting samples or Elecsys HBsAg confirmatory test should be adopted when necessary.