Abstract: In this paper, the Cr:KTP Crystal of two different doping concentration(of 0.03% and 0.l% respectively) are grown using high temperature solution method at different temperatures. The optimal temperature range for these two crystal growings is found; the influence of temperature on Cr:KTP Crystal morphological structure is discussed; Three kinds of defects are studied using both optical and electronic microscopes. The influence of Cr₂O₃ on decomposing temperature of KTP is analysed; The absorption spectrum and the fluorescence spectrum in its Blue-green wave-band are determined; The content of Cr⁴⁺ in Cr:KTP Crystal is estimated. It is proved that the function of Cr:KTP(0.03%) is better than that of Cr:KTP (0.1%).