Objective To establish a detection method for thiourea in wheat flour and flour treatment agents（FTA） by pass-through solid phase extraction purification and high performance liquid chromatography.Methods The samples were extracted by acetonitrile aqueous solution（8：2， V/V）， and purified by PRiME HLB pass-through SPE column. The extract was separated on a XBridge Amide column （4.6 mm×250 mm， 5 μm） with acetonitrile and water as the mobile phase in gradient elution， and detected by high performance liquid chromatography-diode array detector （HPLC-DAD）.Results The linear correlation coefficient （R²） was higher than 0. 9999 in the range of 0.05-20 μg/mL. The limit of detection （LOD） and the limit of quantification （LOQ） were 0.15 and 0.5 mg/kg， respectively. The average recoveries ranged from 95.5% to 103.7% with the relative standard deviation （RSD） less than 5.7% at three spiked levels of LOQ， 2LOQ and 10LOQ.Conclusion The problem of easy gelation and poor dispersion effect of FTA had been solved by the method established in this experiment， while matrix interference in wheat flour and FTA reduced effectively， which protected the chromatographic column. This simple， sensitive， accurate method is suitable for the confirmation and quantification of thiourea in wheat flour and FTA.