Objective To prepare a rapid immunological assay for detecting SudanⅠin foods. Method Optimizing the reaction conditions for anti-SudanⅠ monoclonal antibody prepared in our lab and establishing a competitive inhibition ELISA method for detecting SudanⅠ. It is defined in the study that the optimal concentration of coating antigen was 1 μg/ml, the optimal dilution of the monoclonal antibody was 1:3200 and the optimal action time with substrate was 15 min. Results The regression equations of the detection method was y=-38.541x+131.1 and the correlation coefficients (r) was 0.9841. The detectable limit was in the range of 0.053?0.92 μg/L. The average recovery was 84.72%. Conclusion The benefit of this method for Sudan-Ⅰ is detectable in micro amount, friendly in use, relatively inexpensive and saving time.