Method for resource utilization of phenolic tar

The invention provides a method for resource utilization of phenolic tar. The resource utilization method comprises the following steps: (1) first sulfonation: heating phenolic tar to 100-110 DEG C, slowly adding a sulfonating agent I, continuously keeping the temperature for 1-2.5 hours after the sulfonating agent I is added, and conducting neutralizing with alkali; (2) secondary sulfonation: cooling the sulfonation product in the first step to 50-60 DEG C, adding a sulfonating agent II and water, conducting heating, and continuing sulfonation heat preservation reaction at 85-95 DEG C for 0.5-2.5 h; and (3) subsequent reaction: adding water into the sulfonation product obtained in the step (2), conducting cooling to 50 DEG C or less, slowly dropwise adding acetone, keeping the temperaturefor 10-60 minutes after dropwise adding, dropwise adding a formaldehyde solution, then conducting heating to 90-95 DEG C, preserving heat for 1-2.5 hours, and conducting cooling, replenishing water or not replenishing water