Rosa roxburghii ( R. roxburghii ) is a unique, edible, medicinal fruit rich in vitamin C found in Southwest China. Triadimefon (TDF) is a triazole fungicide that is widely used to control powdery mildew in R. roxburghii . To assess the safety of TDF in R. roxburghii , an LC-MS/MS method was developed for the simultaneous quantification of TDF and its major metabolite, triadimenol (TDN) in R. roxburghii. Both TDF and TDN showed high correlation coefficients (>0.999) for the solvent- and matrix-matched calibrations. The recovery rates of TDF and TDN in R. roxburghii ranged from 90.18% to 100.42%, with a relative standard deviation ( RSD ) of 1.25%-9.22%. The limit of quantification ( LOQ ) was 0.01 mg·kg -1 . The half-life of TDF in R. roxburghii was between 2.74 and 3.07 days, with terminal residues ranging from < LOQ to 1.84 mg·kg -1 . Recommended maximum residue limits ( MRL s) and safe pre-harvest intervals ( PHI s) for TDF in R. roxburghii were 0.5 mg·kg -1 and 21 days, respectively. This study provides essential data for TDF's safe and judicious use in R. roxburghii production.