Suxamethonium chloride in dog meat was extracted by ultrasonic vibration with Na₂CO₃—NaHCO₃ buffer solution，then the supernatant was cleaned-up using WCX solid phase extraction cartridges. The qualitative and quantitative analysis for target was achieved by liquid chromatography-tandem mass spectrometry. The study showed that the suxamethonium chloride concentration had a good linear relationship (r=0.999 87)with mass signal ranging from 0.5～250.0 ng/mL. The recovery was above 96%. The relative standard deviation was below 13%. The limit of determination was 0.004 mg/kg. This is a rapid, sensitive, accurate method for determinating suxamethonium chloride in dog meat.