Objective An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with pass-through solid phase extraction method was developed to determine 7 non-selective cyclooxygenase inhibitors in fish. Methods Samples were extracted with extractant containing 90% acetonitrile and 5% formic acid, and then purified with Oasis PRiME HLB columns. The analysis was performed with Waters CORTECS UPLC C₁₈(100 mm×2.1 mm,1.6 μm)column. The mobile phase was consisted of 0.1% formic acid aqueous solution and acetonitrile containing 0.1% formic acid by gradient elution, and multiple reaction monitoring(MRM)mode with electrospray ionization was used to analyse salicylic acid, piroxicam, naproxen, indomethacin, diclofenac sodium, ibuprofen and phenylbutazone. The effect of the dosages of extractant, formic acid and acetonitrile in cleaning-up agent was studied. The main influence factors and analytical conditions were modified. Results Seven linear calibration curves were obtained with correlation coefficients (r²) ≥0.995 2. The recoveries at three concentrations ranged from 80.3%-95.5%. The limits of quantifications were from 2 to 10 μg/kg. Conclusion The method has the advantages of simple pretreatment, high recovery and good reproducibility which is suitable for the determination of 7 non-selective cyclooxygenase inhibitors in fish.