Objective:To establish an inductively coupled plasma mass spectrometry (ICP-MS) based immunoassay method for the quantitative detection of human chorionic gonadotropin (HCG), and evaluate the clinical applicability of this method.Methods:Sm was selected as element tags, and the HCG quantitative detection system was established by double antibody sandwich method. The dosage of biotinylated antibody and reaction time were optimized. According to EP documents of Clinical and Laboratory Standards Institute (CLSI) and related standards, the analytical performance was evaluated after the establishment of the assay, including the limit of blank (LOB), linearity, precision, recovery, cross reactivity and interference test. And 88 clinical samples were measured using the new method compared to the electrochemical immunoassay (ECLIA) method.Results:Total process completed within 30 min after optimization, and the optimal biotinylated antibody dosage was 0.5 μl. The LOB was 0.29 mIU/ml. The linearity was good within the range of 1.16-8 365.62 mIU/ml with the linear correlation coefficient greater than 0.995 ( R2=0.998 0), the recovery was 97.53%-102.01%. Both intra-and inter-assay coefficients of variation of the high-value sample and the low-value sample were less than 10%. And there was no significant cross-reaction with Luteinizing hormone (LH), follicular stimulating hormone (FSH), and thyroid-stimulating hormone (TSH). The interference bias caused by different concentrations of interference substances was less than 10%. When compared with the ECLIA method for clinical sample detection, the proposed method showed a significant correlation( R2=0.960 0). Conclusion:The proposed ICP-MS base immunoassay for HCG detection has good accuracy, high sensitivity and specificity, and the results of analytical performance verification meet the clinical requirements, which provides experimental basis for the clinical application of this method.