The disclosure belongs to the field of biotechnology, and in particular to a blocking ELISA kit for detecting an antibody to swine acute diarrhea syndrome coronavirus (SADS-CoV) N protein. The kit includes an enzyme plate coated with SADS-CoV N protein, an HRP-labeled mouse anti-SADS-CoV N protein monoclonal antibody (mAb), a positive serum control, and a negative serum control. The kit may detect positive sera diluted at 1:512, with no cross-reaction with positive sera against porcine epidemic diarrhea virus (PEDV), transmissible gasteroenteritis virus (TGEV) and porcine deltacoronavinis (PDCoV) etc., and the intrabatch and interbatch coefficient of variation is less than 10%. The comparison result with the indirect immunofluorescence test shows that the concordance rate of the blocking ELISA kit of the present disclosure is 99.6%, the Kappa value is 0.91, and the blocking ELISA method established by the present disclosure is highly consistent with IFA.