Fatty acid ethyl esters (FAEEs) have great potential for biodiesel fuel production because the raw materials are renewable. Soybean oil (SBO), ethanol, fatty acid ethyl esters, and glycerol are partially miscible in the reaction process. The mutual solubility data of the reaction components are essential for the production design and process operation. In this work, fatty acid ethyl esters were produced by transesterification of soybean oil with ethanol using NaOH as a catalyst. The phase diagrams and tie lines of the fatty acid ethyl esters + ethanol + soybean oil system and fatty acid ethyl esters + ethanol + glycerol system were drawn in the range from (300.15 to 343.15) K. The results indicate that the transesterification reaction is carried out in the ethanol phase. When the temperature increases to 343.15 K, the soybean oil + ethanol mixture becomes a homogeneous phase. The distribution coefficient of fatty acid ethyl esters between the soybean oil phase and the ethanol phase decreases with the increasing concentration of fatty acid ethyl esters. The distribution coefficient of ethanol between the glycerol phase and the fatty acid ethyl esters phase decreases with the increasing concentration of ethanol.