Bidirection layer chromatography was applied to determine citrinin in red qu. The primary phase separated citrinin from other components in red qu and the secondary phase mainly separated citrinin. Trichloromethane∶acetone (9∶1) and benzene∶ethyl acetate∶formic acid (6∶3∶1) were used as developing agents in the primary phase and secondary phase respectively. The results also indicated the minimum detection level as 0.1 μg. The method was simple and feasible and easy for operation.(Tran.by YUE Yang)