The ZnO has been studied widely due to its unique electrical, optical, piezoelectric and magnetic properties [1]. Also, ZnO has potential applications in light emitting diodes, and near-UV or UV laser diodes [2, 3], transparent conductive thin films [1], solar cells [4]. Our previous investigations have shown the possibility to improve the ZnO single crystal quality using strongly absorbed Nd:YAG laser radiation [5]. However, at high laser intensity damage (ablation, fracture, cracking, etc) ZnO crystals were observed [6]. The aim of the present work is to determine damage thresholds of ZnO single crystal by studying the dynamics of laser-induced change of its electrical and optical properties. The effect of UV Nd:YAG laser intensity on the conductivity and optical properties, such as: photoluminescence, Raman, transmittance spectra of hydrothermal ZnO crystal was studied. As a result, three laser intensities characterizing interactions with the crystal have been revealed. The improvement of ZnO crystal quality up to 3.2MW/cm2 was observed. There are the increase of free exciton band intensity and decrease of deep level emission band intensity in photoluminescence spectra. The intensity I=290.0MW/cm2 leads to the formation of “black ZnO”. It is caused by the emergence of Zn nanoparticles with size around 20 nm. XPS analysis and Raman spectra proved the presence of Zn in metallic form. At the same time conductivity of ZnO crystal continues to increase in the whole range of used laser intensities and exceeds the initial value by 300 times. The change of ZnO crystal optical and electrical properties by laser radiation is explained by generation, redistribution and agglomeration of Zn interstitials. Further irradiation of the structure leads to formation ZnO nanoparticles due to oxidation of Zn nanoparticles. 1. X U. Özgür, Y. I. Alivov . A comprehensive review of ZnO materials and devices. J. Appl. Phys., 98(2005). 2. Shimizu, M. Kanbara, M. Hada, and M. Kasuga, Jpn. J. Appl. Phys. 17, 1435 (1978). 3. P. Yang, H. Yan. Controlled Growth of ZnO Nanowires and Their Optical Properties. Adv. Funct. Mater., 323, 323(2002). 4. X. J. Wang, L. S. Vlasenko. Oxygen and zinc vacancies in as-grown ZnO single crystals, - J. Appl. Phys D 42(2009) 5. P. Onufrijevs, A. Medvids, E. Daukšta. Decrease of Point Defect Concentration at a Surface of ZnO/Si Heterostructure by Powerful Laser Radiation. - Adv. Mat. Res., 222, 158(2011) 6. M. Jadraque, C. Domingo. Laser induced effects on ZnO targets upon ablation at 266 and 308 nm wavelengths. Journal of Applied Physics, 104 (2008).