The treatment of growth solution is of great importance to KDP and DKDP crystals. Two kind of solution treating methods are studied in this paper: the organic addictive CS doping in KDP solution and the continuous filtration of the solutions during DKDP crystals growth. The optical transmission spectra for different sectors in crystals, scattering distribution at boundary zone between prismatic and pyramidal sectors and laser damage threshold of crystals are determined for comparison. The results show that moderate dopant concentration of CS would improve the optical quality of KDP crystals: less amount of impurities, higher transmission at ultraviolet band, reduction in evidence of inclusions or cracks inside. In crystal gown with continuous filtration which eliminates effectively the unsolvable particles in the solution, low dislocation density is found distinctly and laser damage performance is improved.