This standard specifies a method for determining the content of malachite green and its homologous colorless malachite green in feed using liquid chromatography and liquid chromatography-tandem mass spectrometry. This standard is divided into high performance liquid chromatography and high performance liquid chromatography-tandem mass spectrometry. High performance liquid chromatography-tandem mass spectrometry is the confirmatory method. This standard high performance liquid chromatography method is suitable for the determination of malachite green and colorless malachite green content in fis meal, compound feed, concentrated feed, additive premixed feed, and concentrate supplements; the high performance liquid chromatography-tandem mass spectrometry method is suitable for Determination of malachite green and colorless malachite green content in fis meal, plant feed raw materials, compound feeds, concentrated feeds, additive premixed feeds, and concentrate supplements. The quantitation limit of malachite green and colorless malachite green measured by liquid chromatography is 10 μg/kg; the quantitation limit of malachite green and colorless malachite green measured by liquid chromatography-tandem mass spectrometry is 1.0 μg/kg.