In the production of acetone oxime methyl ether (AOME) and its related products, AOME usually needs to be separated from the AOME, acetone, and water mixture. As the base data, the liquid-liquid equilibrium data for the AOME-acetone-water ternary system were measured at 293.15 K, 303.15 K, 313.15 K, and 323.15 K, respectively, under atmospheric pressure. Then, the nonrandom two-liquid (NRTL) and T-K-Wilson models were used to correlate the experimental data. The root-mean-square deviation (RMSD) between the calculated values and the experimental data is less than 0.0054 for the NRTL equation, and the RMSD is up to 0.046 for T-K-Wilson equation. Therefore, for this ternary system, the NRTL equation is more suitable than the T-K-Wilson equation for predicting liquid activity coefficients of the system. At the same time, the experimental data also show that the temperature has little effect on the miscibility gap within the experimental temperature range.