Nanocrystallized ZrN coatings have been deposited by DC magnetron sputtering. The effects of target power on the microstructure and mechanical properties of ZrN coatings have been investigated. X-ray diffraction, scanning electron microscope and nano-indentation were applied to characterize the phase structure, morphologies of cross-section and mechanical properties of ZrN coatings. As power increases up to 250 W, ZrN coating exhibits (111) preferred orientation. All coatings showed columnar structure, and the columnar width increased with improved power. These microstructural changes resulted in the increase in hardness with increasing target power.