Abstract: The properties of DKDP solution were studied. The solubility curves of tetragonal phase and monoclinic phase were determined. Also. the transition point, the temperature of tetragonal-monoclinic phase were measured. The influence of stability of DKDP solution, pD value, pyrophosphate anion, and the temperature of growth solution on the growth of DKDP crystal were studied systematically. the good optical DKDP crystal with the growth rate of 6.2 mm/d was achieved, and the extinction ratio was measured. Experiments show that the DKDP crystal grown at high velocity has the same optical homogeneity as the crystal grown by using normal slow-cooling method.