The w astew ater from gum benzion production contains benzaldehyde, cyanide, gum benzoin and ethyl benzoate.When the cy anide is determined by iso-nicotinic acid-py razalon method, the ethyl benzoate is distilled and goes into NaOH abso rptio n liquid w ith cy anide in the process of pre-distillation, because it s boiling point is low.Thus the absorption liquid produces a great deal of foam and feculence.This disturbs the sequent colorimetric determination seriously.To separate the g rease and water, chloroform ex t raction is used to remove the grease.Then the cyanide in w ater can be determined.Experiments show that this method has ideal unanimity,less errors, and high recurrence rate.It is an effective w ay to eliminate organic g rease disturbance.