ZnO is a member of group II-VI semiconductors which has attracted great scientific and technological interest. An important feature of this group of compounds is their wide band gap, which is promising for opto-electronics applications. ZnO has two main phases, hexagonal wurtzite and cubic zinc-blend structures, and two high pressure phases, rock-salt and CsCl structures. Because of the wide application of this semiconductor and moreover, importance of new phases for modern applications, in this project we search for the possible unknown phases of this material. Our aim is to employ evolutionary algorithm as an efficient structure search technique for finding possible novel meta-stable structure of this compound. This task will be performed by using the USPEX structure search package . This package needs very little initial data about a material to investigate its various configurations in the framework of evolutionary algorithm and find the stable and meta-stable structures of the system. The total energy of the configurations is calculated by the Quantum Espresso package. This package is based on density functional theory and we use the PBE formulation of the generalized gradient approximation (GGA) in this work. In this thesis, we present the results of our structure search in systems with 4, 6, 8, and 12 atoms per unitcell and then study the phonon, electronic, and mechanical properties of superior structures.