The solubility of urea phosphate in water + phosphoric acid from (277.00 to 354.50) K was measured by a synthetic method at atmospheric pressure, where laser monitoring observation equipment was used. The experimental data were correlated with the Apelblat equation, and the average relative deviation (ARD) between experimental data and calculated data was only 1.61 %. The result is a necessary complement to the data of urea phosphate solubility.