ZnO is an n-type semiconductor having a hexagonal wurzite structure. ZnO exhibits good piezoelectric, photoelectric and optical properties and might be a good candidate for an electroluminescence device like an UV laser diode. But the important problems, such as substrate kinds and substrate temperature are raised its head, so they need to optimize deposit condition. Because these devices are very small and films are very thin, those are often prepared in limited quantities and shapes unsuitable for the extensive mechanical test. In this present work, ZnO thin films are prepared on the glass, GaAs (100), Si (111) and Si (100) substrates at different temperatures by the pulsed laser deposition (PLD) method. ZnO was evaluated in term of crystalline through X-ray diffraction (XRD), mechanical properties such as hardness, elastic modulus through nano-indenter. XRD measurements indicate that the substrate temperature of 200-500, 200-500, 300-500, and 300-500oC was the optimized conditions of crystalline for the glass, GaAs (100), Si (111), and Si (100) substrates, respectively. In spite of the films deposited on the different substrates, the films always show (002) orientation at the optimized conditions. Mechanical properties such as hardness and elastic modulus are influenced substrate crystallization. In case of Si (111) substrate, hardness and elastic modulus are about 10, 150GPa, respectively.