Abstract: A rapid screening method using DBDI-MS/MS was established for MG and LMG residues in aquatic products. The samples were extracted and purified,and then injected under the conditions of ionization temperature of 230 ℃ and He gas flow rate of 3 L/min using DBDI in the positive ion mode. The determination was conducted by tandem mass spectrometry in positive ESI mode under multiple reaction monitoring(MRM)mode. Under the optimal conditions,the experimental data of MG and LMG showed a good linear relationship between the signal and the concentration in 1~20 μg/L,with correlation coefficient(r)of 0.9951 and 0.9939. Moreover,the recoveries of MG and LMG were between 61.8% and 78.4% at three spiked levels. This method without tedious pretreatment and chromatographic separation,was simple and rapid,can meet the requirement of rapid screening and analysis of large quantities of samples.