Objective A new liquid liquid extraction-ultra performance liquid chromatography-tandem mass spectrometry method was developed for the determination of sodium pentachlorophenolate in chopping board. Methods Samples were ultrasonic extracted with 50% methanol/aqueous solution(1% ammonia)for 10 min, followed by extraction with n-hexane-dichloromethane(8∶2,V/V). Then the analyte was evaporated to dryness and dissolved with 0.01% ammonia-methanol. After being ultra performance separated on a column using mobile phase, the analytes were detected under electrospray source negative ion (ESI-) multi reaction monitoring (MRM) mode by tandem mass spectrometry. Results The limit of detection for sodium pentachlorophenolate was 0.2 μg/kg. The result showed that the average recovery at spiking level of 1,4,20 μg/kg ranged from 101.4% to 108.9% and the relative standard deviation was 3.5%-7.8% (n=7).The method had been successfully applied to the measurement of sodium pentachlorophenolate in 60 chopping board samples shopped from Lishui markets, and one of the samples had sodium pentachlorophenolate with 1.16 μg/kg . Conclusion The liquid liquid extraction method is easy, economic and efficient. The ultra performance liquid chromatography-tandem mass spectrometry method is rapid and accurate to confirmatively detect sodium pentachlorophenolate in chopping board.