Abstract: The phenolic substances in the bio-oil fractions collected at different temperature intervals were extracted by barium ion precipitation method at different concentrations of NaOH reagent, reaction temperatures and reaction times, and the extraction effect was analyzed by GC-MS. The results show that the effect of barium ion precipitation on guaiacols separation is more outstanding. The temperature (30-50℃), concentration of NaOH (1.0-6.0 mol/L) and reaction time (10-40 min) have great influence on the extraction rate of guaiacols. The optimum reaction parameters include the NaOH solution of 5.5 mol/L, the temperature of 35℃ and the reaction time of 20 min. Under the optimum condition, the extraction rate of guaiacols in the three fractions of low temperature water, low temperature oil and high temperature are 34.1%, 33.8% and 33.5%, respectively.