In order to improve the biodegradability of coal pyrolysis wastewater and ensure the stable operation of biochemical device, it is necessary to clarify the toxicity source of wastewater and evaluate the toxicity reduction performance of pretreatment process. In this paper, the pollutants were classified by trioctylamine extraction combined with macroporous resin fractional adsorption to overcome the analysis problems of peak area overlap and large difference. Then the toxicity of the analyzed pollutants was evaluated by  luminescent bacteria method, and the key pollutants in wastewater were determined. Finally, the reduction of biological toxicity, chemical oxygen demand, total phenol content and key pollutant content of wastewater treated by four conventional liquid-liquid systems were evaluated to provide theoretical support for the improvement of pretreatment process. The results show that phenols are the most important pollutants contributing to the biological toxicity of coal pyrolysis wastewater, and p-cresol is the most toxic. The type, position and number of substituents on the benzene ring of phenolic compounds have a significant impact on biological toxicity. Heterocyclic compounds have more residues in biochemical effluent and contribute greatly to the toxicity of wastewater. The toxicity reduction rates of four conventional extractants to wastewater are butyl acetate (96.6%), methyl isobutyl ketone (95.1%), isopropyl ether (92.4%) and trioctylamine (79.5%). The reduction rate of total phenol content in the wastewater after trioctylamine extraction is the highest, but the reduction rate of chemical oxygen demand and biological toxicity is the lowest. It indicates that the complex extractant is not suitable for the treatment of complex phenol containing wastewater. Butyl acetate and methyl isobutyl ketone can widely remove various key pollutants, so the reduction rate of chemical oxygen demand and toxicity is high, which is suitable for the extraction treatment of pyrolysis wastewater.