Nanocomposite Ni-Al2O3 thin film containing nanosized Al2O3 particles had been grown on steel substrate by ultrasonic-electrodeposited technology. The optimum technological parameters of nanocomposite Ni-Al2O3 thin films were obtained by experiments and analysis. X-ray diffraction analysis was utilized to detect the crystalline and amorphous characteristics of Ni-Al2O3 thin films. The surface morphology and metallurgical structure were analysed by high resolution transmission electron microscope, and scanning electron microscope. The test results showed that nanocomposite Ni-Al2O3 thin films prepared by proper ultrasonic-electrodeposited method consist of nanometer-sized Al2O3 particles and nickel grains. And the Al2O3 nanoparticles and Ni grains diameters in thin films are about 40nm and 80nm, respectively.