Abstract: A determination method of four lipophilic shellfish toxins ( Okadaic Acid, OA; Spirolides1, SPX1;Dinophysistoxin1, DTX1; Azaspiracid1, AZA1) in edible shellfish products by Qu ECh ERS technology combined with high performance liquid chromatography- high resolution time of flight mass spectrometry ( HPLC- TOF- MS / MS) was established.Qu ECh ERS technology was used to extract and purify the samples.Four lipophilic shellfish toxins were separated by C18 column and detected by HPLC- TOF- MS / MS at electrospray ionization ( ESI) mode. After importing data by Peak View software, TOF-MS/ MS quality precision, isotopic distribution and retention time of each compounds, as well as the MS2 chromatogram of the standard solution and sample were compared to qualitatively analyze the target compound.Finally, the software of Multi Quant was used to quantify by external standard calibration method.The calibration curves of OA and DTX1 showed good linearity in the range of 2.0 ~ 100 μg / L, the limits of detection ( LOD, S / N = 3) were 10 μg / kg, while the LOD of AZA1 and SPX1 were 2.0 μg / kg, the ranges werebetween 0.5²0 μg / L.The correlation coefficients ( R2) were all above 0.997.The average spiked recoveries of four shellfish toxins at three concentration levels were between 75.6% ~ 94.1%, and RSD all below 10%. 20 import &export samples including mussel, octopus, geoduck and oyster were screened by the developed method, SPX1 was found in 8 samples and AZA1 in 2 samples. The developed method was easy, quick, sensitive, reproducible and suitable for the determination of lipophilic shellfish toxins in shellfish products.