The invention discloses a detoxification method for a wood fiber raw material pre-hydrolysis sugar liquid. According to the detoxification method, a pre-hydrolysis concentrated sugar liquid obtained after dilute sulphuric acid steam explosion pretreatment is taken as a raw material and an ionic liquid is taken as an extraction agent for removing of fermentation inhibitors in the wood fiber raw material pre-hydrolysis concentrated sugar liquid, wherein the ionic liquid is a disubstituted imidazole cationic liquid. The detoxification method has the advantages that the organic ionic liquid is adopted for extraction treatment on a wood fiber raw material pre-hydrolysis concentrated sugar liquid, and the treatment result shows that on the premise that a little fermented sugar is lost, the removing rates of formic acid, acetic acid, levulinic acid, furfuraldehyde, hydroxymethyl furfural and total phenolics in the prehydrolysis concentrated sugar liquid reach 64.54%, 54.88%, 100%, 100%, 87.08% and 70.44% respectively; in the same period, the sugar utilization rate is improved by 74.34%, the ethanol yield is improved by 82.91%, and the fermentation circle is shortened.