Nickel oxide (NiO) films were deposited by using a homemade DC reactive magnetron sputtering system at different working pressure in the range (0.05-0.14)mbar. The effect of working pressure on the structure, surface morphology, optical of NiO films was investigated. X-ray diffraction (XRD) results suggested that the deposited films were formed by nanoparticles with average particle size in the range of (8.145-29.195) nm. And the films are identified to be polycrystalline nature with a cubic structure along (111) and (101) orientation also Ni2O3 was found by XRD. The texture of the films was observed using SEM and AFM, it was observed that the grain size was increased with working pressure. The energy band gap was found to be in the range of (4.1 eV to 3.9 eV) When the film thickness varying from 73 nm to 146.9 nm.