A method was developed for the simultaneous determination of nine mycotoxins in wheat flour by ultra-high performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS) combined with QuEChERS (quick, easy, cheap, effective, rugged and safe) pretreatment. Samples were extracted with acetonitrile/formic acid solution (98.0:2.0, V/V), salted out with a QuEChERS salt pocket, and then purified with a dispersive solid phase extraction (dSPE) tube. The target compounds were separated by UPLC and detected in the positive ion mode. Measured accurate mass-to-charge ratios of the nine mycotoxins were obtained in the full scan mode with a relative deviation not more than 1.91 × 10^-6 compared to the theoretical value, indicating accurate qualitative analysis of these compounds. A tandem mass spectral library for simultaneous screening and quantitation of the mycotoxins was built based on characteristic fragment ions. The linear ranges were 0.25–100 μg/L for all target analytes. The limit of quantification (LOQ) ranged from 0.30 to 3.00 μg/kg. Average recoveries at three spiked levels were in the range of 70.2%-112.0% with relative standard deviation (RSD) of 0.2%–4.5%. This method is useful for the high-throughput screening and confirmation of mycotoxins in wheat flour.