Oxidation of trimethylamine ((CH3) 3NO) is widely distributed in pork, fish and shrimp, it has a special flavor. Trimethylamine is reduced to trimethylamine ((CH3) 3N) under the action of bacteria.Shielding= 0.9999, n = 6), the relative standard deviations were 3.1% -5.9%, the recoveries were 95.0% ~ 97.7%, and the relative standard deviations (RSDs) were in the range of 0-25 μg / ml, And the method is simple, fast and accurate.