Abstract: C-reactive protein (CRP) is a biomarker of thrombosis in atherosclerosis. Therefore, it is important for us to regularly detect the level of CRP in serum, which would predict cardiovascular disease’s occurrence and development. A radioimmunoassay method was established for detecting CRP in our lab. The measurement range of the assay is 1-50 mg/L, sensitivity is 0.30 mg/L, recovery rate is 91.7%-114.0%. Intra- and inter-assay variation coefficients are 3.4% and 6.3%, respectively. The correlation coefficients between measured and expected values are more than 0.990 after serial dilution of the serum samples with high concentrations of CRP. The kit would provide a convenience in the control, treatment and prognosis of cardiovascular disease.