Ergot alkaloids (EAs) are mycotoxins produced by Claviceps and are present in cereals and their products; their residues pose significant threats to human health through food consumption, resulting in ergotism and sickness. Herein, a sensitive and rapid method for the determination of 11 EAs in cereals and their products using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) were developed. Eleven EAs were extracted with 20 mL acetonitrile-200 mg/L ammonium acetate solution (80∶20, v/v) for 15 min using the vortex shock method followed by 15 min of ultrasonication. The mixture was subsequently centrifuged at 10000 r/min for 10 min, and the supernatant was purified by a Captiva EMR-Lipid column. Target analytes were separated on an ACQUITY UPLC HSS T3 chromatography column (100 mm×3 mm, 1.8 μm) at a column temperature of 40 ℃ and a flow rate of 0.4 mL/min using an injection volume of 5 μL. Gradient elution was performed using 1 mmol/L ammonium acetate solution and acetonitrile as mobile phases. Data were collected in electrospray positive-ion (ESI+) and multi-reaction monitoring (MRM) modes, and quantified using matrix-matched standard curves. The 11 EAs exhibited good linearities in their linear ranges, with correlation coefficients (r2) of 0.9933-0.9999, with limits of detection (LODs) and limits of quantification (LOQs) of 0.002-0.2 and 0.006-0.6 μg/kg, respectively. Recoveries and relative standard deviations (RSDs) of the 11 EAs in matrix samples of wheat flour, coix seed, wheat flour products, and corn flour at low, medium, and high spiked levels were 80.1%-118% and 0.2%-13.3%, respectively. The established method was used to determine EAs in 240 wheat flour, 80 corn flour, 30 rice, and 30 coix seed samples, as well as 146 wheat flour products, with the detection rates of the 11 EAs of 0.57%-20.3%. A maximum total content of EAs of 56.7 μg/kg was recorded for a single sample. The sample pretreatment process used in this method is simple and fast, and the detection method is highly sensitive, with accurate and reliable results obtained. This method is suitable for simultaneously determining various EAs in cereals and their products. The results of this study provide valuable information for future EA risk-assessment studies.