In order to obtain the basic data of the process simulation and design of both the extraction of the phenolic compounds from the highly-concentrated phenolic wastewater in coal chemical industry by using methyl isobutyl ke- tone (MIBK) and the corresponding solvent recycling at an industrial operating temperature,the liquid-liquid equilibrium (LLE) data of a MIBK-phenol-catechol-water quaternary system were measured at 70 ℃ under the atmospheric pressure,and the reliability of the LLE data was ascertained by using the Hand and Othmer-Tobias equations.Moreover,the experimental data were thermodynamically correlated by adopting the NRTL and UNIQUAC models,and binary interaction parameters were calculated by using simulation software.The results show that the calculated data based on the NRTL and UNIQUAC models accord well with the measured data,and the root-mean-square-deviations (RMSD) of the two models are less than 0. 02,which means that the binary inte- raction parameters obtained through the two models can be used to precisely predict the LLE data.Therefore,it can be concluded that the MIBK extraction at high temperatures is of good practical value in industry from the per- spectives of anti-blockage and extraction efficiency.