A simple and efficient method based on QuEChERS and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of diafenthiuron and itss degradation products in tea. The sample was extracted with acetonitrile and cleaned up with QuEChERS. In the chromatographic analysis, three target compounds were separated on a C₁₈ column (150 mm × 4.6 mm, 3.5 μm) with the gradient elution using the mobile phases of acetonitrile and water containing 0.1% acetic acid. The mass analyzer was performed using positive scan mode with MRM monitor using external standard method. The results showed that the limits of quantitatiom ( LOQ, S /N≥10) of diafenthiuron, diafenthiuron-methanimidamide and diafenthiuron-urea were 0.01 mg/kg, 0.005 mg/kg, 0.003 mg/kg, respectively. The average recoveries of the three compounds spiked at three level concentration were in the range of 62.2%～99.6%， with the relative standard deviations( RSDs) of 1.3%～9.4%. This method is simple, fast, credible and high sensitivity can be applied to simultaneous identification and quantitation of diafenthiuron and its degradation products in teas, and the same time this method can effectively reducing the degaragation of diafenthiuron in the pretreatment process. This method meet the requirements for determination of diafenthiuron and its degradation products in tea.