The present invention relates to a kit and a method for detecting creatinine. A creatinine assay kit comprises the first reagent set and the second reagent set; the first reagent set contains N-(2-hydroxy-3-sulfopropyl) -3,5-dimethoxyaniline or its salts, N-ethyl-N- (2-hydroxy-3-sulfopropyl) -3,5-dimethoxyaniline or its salts, and combination thereof, and the second reagent set contains 4-aminoantipyrine. The kit and method of the present invention can decrease interference caused by calcium dobesilate and/ or etamsylate in sample when quantifying creatinine amount in a biological sample.