The invention provides a methimazole detection method, which comprises the following steps of mixing methimazole with a first AuNPs solution to obtain a mixed solution; irradiating a first mixed solution formed by mixing the mixed solution with a first fluorescent N/S-CQDs solution with ultraviolet light to obtain a fluorescence spectrogram of the first mixed solution; irradiating a second mixed solution formed by mixing a second AuNPs solution and a second fluorescent N/S-CQDs solution with ultraviolet light to obtain a fluorescence spectrogram of the second mixed solution; obtaining the content of the methimazole according to the fluorescence spectrogram of the first mixed solution and the fluorescence spectrogram of the second mixed solution. The methimazole detection method provided by the invention uses the fluorescent N/S-CQDs as energy donors and AuNPs as energy receptors to construct a complex fluorescent probe, and the methimazole is detected by using the complex fluorescent probe. Compared with high performance liquid chromatography, flow injection spectrophotometry and the like, the cost is low, and the operation is easy.