The solubility of ammonium dihydrogen phosphate (MAP) was measured at the temperature range from 283.2 to 343.2 K by using dynamic and static methods in water-ethanol system. The experiment results showed that the solubility of MAP increased with the increase of the investigated temperatures under the constant ethanol concentration and decreased with increasing concentration of ethanol with isothermal operations. The solubility of MAP in water-ethanol system was fitted by the modified Apelblat equation, the correlation coefficient square was greater than 0.990, and the average of the root-mean-square deviation was 4.346 x 10(-4), which indicated that the experiment data was well in agreement with the calculation value.