Abstract: Objective: The method of QuEChERS-UPLC was established for the simultaneous determination of cyhalofop-butyl and cyhalofop-acid residues in cereals and oilseeds. Methods: The accurately weighed 2.0 g and 5.0 g sample was extracted with 0.1% formic acid water-acetonitrile (1:1, V/V) as extractant, and then purified with dispersive solid phase extraction adsorbents, such as N-propyl ethylenediamine (PSA), C₁₈, sodium chloride, anhydrous magnesium sulfate, etc. After the purified solution was filtered through a 0.22 μm filter membrane, it was eluted with 0.1% phosphoric acid aqueous solution-methanol-acetonitrile as the mobile phase for gradient elution, separated by ACQUITY UPLC BEH C₁₈ (50 mm × 2.1 mm, 1.7 μm) chromatographic column, analyzed and detected by UPLC, and quantified by external standard method. Results: In the range of 0.002~5 μg/mL, the mass concentration of cyhalofop-butyl and cyhalofop-acid showed a good linear relationship with the peak area, and the limits of quantification in grains and oilseeds were 0.01 mg/kg and 0.02 mg/kg, respectively. The recoveries of cyhalofop-butyl and cyhalofop-acid in cereals were 89.23%~101.12% and 87.98%~100.02%. Those in oilseeds were 85.12%~92.34% and 82.63%~89.55% respectively. The relative standard deviation was 1.1%~3.3%. Conclusion: The method used in this experiment has a simple pretreatment process, accurate and efficient detection process, and its sensitivity and accuracy meet the requirements of pesticide residue detection. It is suitable for the detection of cyhalofop-butyl and cyhalofop-acid residues in grains and oilseeds.