Abstract: A label-free electrochemiluminescence (ECL) immunosensor for sensitive detection of cardiac troponin I (cTnI) was constructed based on MoS₂ quantum dots (MoS₂ QDs)/potassium persulfate (K₂S₂O₈) ECL system. The luminescent material MoS₂ QDs was combined with reduced graphene oxide (MoS₂ QDs-rGO) to construct the immunosensor. The large surface area of rGO could carry a large amount of MoS₂ QDs. The MoS₂ QDs-rGO exhibited good ECL performance. Under the optimized conditions, the proposed ECL immunosensing method showed good analytical performance for cTnI detection, and the linear range was 1.0×10^-9~1.0×10^-4 g/L (R=0.998) with a detection limit of 4.9×10^-10 g/L (R_SN=3). The proposed method was applied for the determination of cTnI in human serum samples, and the analytical results were consistent with the results of Xinyang Central Hospital. The recoveries of the method were 98.0%~110.0%.