Abstract: UHPLC-MS/MS was applied to the rapid determination of 9 algal toxins in surface water. The surface water sample was filtered by strainer. After centrifugation, the supernatant was obtained. Waters Acquity BEH130 chromatographic column was used as stationary phase, and the mixture of 0.1% (φ, the same below) formic acid solution and acetonitrile (containing 0.1% formic acid) mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and multi-reactions monitor mode were adopted in MS/MS. Linear relationships between values of peak area and mass concentration of the 9 algal toxins were kept in definite ranges. Detection limits of the method ranged from 0.084 to 0.175 μg·L^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 79.4%-113%, with RSDs (n=7) in the range of 5.1%-14%.