ABSTRACT: Objective To establish the liquid chromatography-mass spectrometry method based on AQC derivation for BMAA and its isomers in algal health products, and investigate the pollution levels of algal health products from China. Methods The samples were treated by acid hydrolysis, nitrogen concentration and AQC derivatization, and then analyzed by ultra-performance liquid chromatography-tandem mass spectrometry, quantified by internal standard methods of two commercial isotope standards. Results In the linear range of 0.25 ~ 100 μg/L, the correlation coefficients of BMAA toxions were all above 0.998. When the samples were 15 mg and the volume were 20.0 mL, the detection limits of BMAA, AEG and DAB were 133, 133 and 200 μg/kg, respectively. And the quantitative limits were 443, 443 and 667 μg/kg, respectively. The recoveries were between 86% ~ 126%, with the relative standard deviations (n=6) between 1.1% ~ 14%.The detection rate for DAB was the highest in all samples (86%), followed by AEG (23%) and BMAA (14%). The concentrations of DAB, AEG and BMAA in the detectable samples were between 385 ~ 2305 μg/kg, 250 ~ 518 μg/kg and 472 ~ 698 μg/kg, respectively. Conclusion The established method based on AQC derivation LC-MS/MS method is more efficient and accurate. The levels of BMAA toxins in domestic algae health products were relatively high, it should be paid more attention and to strengthen the supervision.