A reliable and sensitive method for rapid simultaneous determination of two type A (T-2 and diacetoxyscirpenol) and two type B (3-acetyldeoxynivalenol and Fusarenon X) trichothecenes was developed and successfully applied for detecting trichothecenes in potato tubers by ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry. The established method was further evaluated by determining the linearity (R ≥ 0.9995), recovery (113.28-77.97%), precision (relative standard deviation ≤ 5.89), and sensitivity (limit of detection, 0.002-0.005 μg/g; limit of quantitation, 0.005-0.015 μg/g). The method proved to be suitable for simultaneous determination of T-2, diacetoxyscirpenol, 3-acetyldeoxynivalenol, and Fusarenon X in potato tubers inoculated with Fusarium sulphureum . In addition, it was found that T-2, diacetoxyscirpenol, 3-acetyldeoxynivalenol, and Fusarenon X could be predominantly detected in the lesion, and the toxin could also be identified in tubers without any disease symptoms. The experimental results also indicated that the concentration of toxin in the susceptible cultivar (Longshu No. 3) was significantly higher than that in the resistant cultivar (Longshu No. 6).