The phase diagram of flunixin meglumine + meglumine system has been investigated with the method of differential scanning calorimetry (DSC). The results show that the flunixin meglumine and meglumine hold the formation of a simple eutectic mixture. The linear velocity of solidification of both pure components and the eutectic mixture was determined at different undercooling rates. The fusion enthalpy and the linear velocity of crystallization indicate the nonideal properties of the eutectic mixture in the melt. The roughness parameter of the eutectic system was calculated from the enthalpy of fusion value. The anisotropic and isotropic crystallizations of flunixin meglumine, meglumine, and the eutectic mixture were studied.