Abstract: A simultaneous method was developed for the determination of florasulam and fluroxypyr in wheat and soil using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) . The storage stability of florasulam and fluroxypyr in wheat under cold storage condition was studied. The final residue and dissipation of the two herbicides in wheat and soil were also determined by this new method. At the spiked level from 0.005 mg/kg to 1 mg/kg, the average recoveries of florasulam and fluroxypyr in wheat and soil were 82%-108%, and the relative standard deviations were 0.41%-11%(n=5) . The results showed that the method is reliable and practical for pesticide residue analysis. After storage at –20℃ for 365 d, the decrease of residues of florasulam and fluroxypyr in wheat is less than 30%, which is in the line with the requirements of the storage stability test criteria for pesticide residues in plant-derived agricultural products. The dissipation half-lives of florasulam in wheat and soil was 4.4-8.1 d and 2.4-9.3 d, respectively.The dissipation half-lives of fluroxypyr in wheat and soil was 7.9-10.6 d and 11.8-24.8 d, respectively. Under the same experimental conditions, the degradation rates of florasulam in plants and soil were faster than those of fluroxypyr. When the formulated pesticide of florasulam and fluroxypyr 15% suspensions (SE) was sprayed once at the recommended dose (active ingredients: 180 g/hm²) and high dose (active ingredients: 270 g/hm²) in wheat fields, the florasulam and fluroxypyr residues were not detected in wheat during the harvest period.