Objective To establish a method for the determination of chlorate and perchlorate in seasoning samples by ultra-performance liquid chromatography tandems mass spectrometry (UPLC-MS/MS). Methods Seasoning sample was ultrasonically extracted with acidic acetonitrile solution, and then purified with a graphitized carbon black (GCB) cartridge and an Ag/H cartridge. UPLC-MS/MS analysis was conducted under multi-reaction monitoring mode with isotope-labelled internal standard calibration for quantification. Results Chlorate and perchlorate showed a good linearity (R²≥0.99) in the range of 1-1 000 μg/L and 0.1-100 μg/L, respectively. The limits of detection for chlorate and perchlorate were 3.0 μg/kg and 0.3 μg/kg, as well as the limits of quantification were 10 μg/kg and 1.0 μg/kg, respectively. The average recoveries of two compounds in seasoning samples at three spiked levels were 86.5%-113.7% and the relative standard deviations were 1.8%-15.3%. The detection rates of chlorate and perchlorate from 122 seasoning samples were 76.2% and 93.4%, with the maximum concentration of 30.4 mg/kg and 12.3 mg/kg, respectively. Conclusion The method is suitable for qualitative and quantitative analysis of chlorate and perchlorate in seasoning. Further study should be focused on the perchlorate in seasoning products since its relative prevalence contamination.