In order to investigate the depolymerization characteristics of alkali lignin in solvent /water mixture systems，four systems，namely ethanol /water，ethyl acetate /water，ethylene glycol /water and pure water，were selected to perform experiments． The results show that ( 1) ethanol /water mixed solvent medium helps to obtain the highest yield of liquid products and total phenolic compounds; ( 2) under the optimal reaction condition ( a temperature of 300 ℃，a reaction time of 30 min，a rotational speed of 500 r/min，a formic acid dosage of nickel of 10% and an ethanol-to-water volume ratio of 40∶60) ，the yields of liquid products and total phenolic compounds are 73. 88% and 14. 45% ，respectively; and ( 3) after the flashing at 200 ℃ and the pyrolysis at 500 ℃ of the liquid products，the phenolic compounds derived from lignin's basic structural unit are the most abundant，thus greatly increasing the yield of monophenol． Moreover，the methyl aryl ether bond of the distillation residue may break down during the pyrolysis process，which leads to the formation of a certain amount of catechol． All these above-mentioned statements provide guidelines for the quality improvement and utilization of liquid products．