A method for the simultaneous determination of multiple phenolic compounds in aquatic products was investigated because there is a lack of standards for the detection of multiple phenolic compounds in aquatic products at home and abroad， and the existing detection methods cannot detect multiple phenolic compounds at the same time. A modified QuEChERS pretreatment method was used to optimize the mass spectrometry conditions， extractant and extractant dosage， and the response surface Box-Behnken method was used to optimize the clean-up agent. The results showed that the detection limits of the method for the determination of 18 phenolic compounds were in the range of 0.001-0.012 mg/kg， the spiked recoveries were 83.1%-107.7% and the relative standard deviations were 1.9%-9.5%. The method was applied to the actual samples and the results showed that phenolic compounds were detected in all molluscs， with scallops and razor clams showing the most serious phenolic contamination， followed by oysters， mussels and sea cucumbers， and squid the least contaminated. The method was developed to provide a technical reference for the development of national standards for the detection of phenolic compounds and the safety regulation of aquatic products.