KDP crystals doped with Chicago Sky Blue 6B（CSB-6B） were grown by traditional lowering temperature method.The optical properties and structural perfection of KDP crystals were investigated by transmittance spectra and high-resolution X-ray diffraction,respectively.The results indicate that CSB-6B tends to be incorporated into the pyramidal sector of KDP crystals（PyS-KDP） and lead to inclusions parallel to（101） face.Additionally,the transmittance of as-grown KDP crystals decreases as the amount of CSB-6B increases. Moreover,the rocking curves of PyS-KDP suggest that CSB-6B can deteriorate the structural perfection of PyS-KDP.
