Abstract: A portion of sample of aquatic product (2.00 g) was extracted ultrasonically for 5 min with 10 mL of CH₃OH after mixing with 2 g of anhydrous sodium sulfate, and centrifuged for 5 min. The supernatant was taken and purified by swirling for 1 min with 500 mg of neutral alumina and 15 mg of graphitized carbon black, and then centrifuged for 5 min. The supernatant was taken and evaporated to near-dryness by N₂-blowing at 40℃. The residue was dissolved in and with its volume made up to 2.0 mL of a mixed solution of mobile phase A-mobile phase B with the volume ratio of 1:1. The solution was then filtered through 0.22 μm filtering membrane and the filtrate was used for determination of 3 cyanobacteria toxins by high performance liquid chromatography-high resolution mass spectrometry. In the liquid chromatography separation, Hypersile Gold C₈ column (150 mm×2.1 mm, 3 μm) was used as stationary phase and mixtures of solution (A) and (B) in various ratios were used as mobile phases in the gradient elution. Electrospray ionization with mode of switching of cation and anion was adopted in mass spectrometry determination. Matrix matching was used in preparation of standard curves of the 3 cyanobacteria toxins to overcome matrix effects. Standard curves of the 3 cyanobacteria toxins were obtained in the same range of 10-200 μg·L^-1, with their same detection limits (3S/N) of 5 μg·kg^-1. Values of recovery found by test for recovery by standard addition method were in the range of 68.3%-104%, and values of RSDs (n=6) were found ranged from 7.7% to 17%.