The metastability limit of K2co3-added solution is shown in Fig. 2, in comparison with the pure system. It is obvious from the figure that the zone widths for both the solutions decrease as the increases. At the same time, the addition of K2co, temperature enhances the metastable zone width of KDP solutions for all temperatures, and makes the KDP solution more stable. Also, it was observed that during the experiment the number of tiny reduced in the case of the K2co3-added nucleation was appreciably crystals formed by spontaneous solution compared with the pure one. The change in pH of the KDP solution by the addition of dopant K2Co3 has a major role in the suppression of spontaneous nucleation. The addition of K2Co3 can make KDP solution more stable than other additives and increase the growth rate of the KDP crystal under higher supercooling. At the same time, the addition of K2co3 enhances the zone width of the KDP solution for all the temperatures.