Abstract: A reliable QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis method was developed for residual simultaneous determination of cyazofamid and its metabolite, 4-chloro-5-p-tolylimidazole-2-carbonitrile (CCIM), in cucumber and soil. The samples were extracted by V (acetic acid) : V (acetonitrile) = 1:99, and separated by UPLC with a waters XBridge-C₁₈ column (150 mm × 2.1 mm, 3.5 μm). Targeted compounds were analyzed using UPLC-MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI⁺). Under the optimum condition, when the concentrations of cyazofamid and CCIM were 0.005-1 mg/kg, the linear relation was great (R² > 0.999). When the fortification levels were 0.01, 0.05 and 1 mg/kg, the recoveries of cyazofamid in cucumber and soil were 84%-95% with relative standard deviations (RSD) of 1.2%-3.3%, and the recoveries of CCIM was 84%-103% with RSD of 2.0%-3.9%. The dissipation dynamics of cyazofamid in soil and cucumber accorded with the first-order kinetics equation. The half-lives of cyazofamid in cucumber was 1.7-4.0 d, and in soil was 6.6-9.6 d, respectively. This method is simple, rapid and time-saving. As the sensitivity, accuracy and precision are satisfied with the requirements of the pesticide residues analysis.