Co-TiO₂ nanocomposite film is a novel spin electron material with good biocompatibility, attracting wordwide attention in recent years. However, during the preparation process, the magnetic metal is exposed to the oxidizing atmosphere, which tends to form partial oxidation, thus affecting the properties of the tunnel magnetoresistance. In order to inhibit the oxidation of magnetic metal and improve the metal state, Co-TiO₂ nanocomposite films were prepared by strong magnetic target co-sputtering. In this method, the strong magnetic target head has the characteristics of high magnetic field intensity and uniform distribution, which can significantly improve the sputtering particle energy and sputtering rate. This process could reduce the probability of oxidation caused by high energy particle collision during sputtering. Therefore, the method can inhibit the oxidation of metal Co, improve the spin polarizability of nanocomposite films. The Co-TiO₂ nanocomposite film is mainly composed of amorphous TiO₂ matrix and dispersed Co particles. By adjusting the particle size and distribution of Co particles, the electrical properties of the films show the transition from metal state to insulated state. Moreover, the magnetic properties of the films show the transition from ferromagnetic state to superparamagnetic state. When the Co content is 51.3at%, the Co-TiO₂ nanocomposite films exhibit high metal state and high resistivity, and room temperature tunneling magnetoresistance up to 8.25%. By strong magnetic target co-sputtering, the room temperature magnetoresistance performance is improved in Co-TiO₂ nanocomposite films, which is valuable for the study of magnetic metal-oxide nanocomposite films.