Objective To prepare aluminum nitride thin films with excellent performance. Methods Aluminum nitride thin films were deposited by RF inductively coupled plasma ion source enhanced DC magnetron sputtering technique, different orientations of aluminum nitride thin films were deposited on Si(100) and glass by changing the pressure. The crystal structure, orientation, surface morphology and surface roughness of the aluminum nitride thin films were investigated by X-ray diffraction, SEM and AFM, respectively. UV-spectrophotometer was used to measure the transmittance of aluminum nitride thin film, and the optical band gap of aluminum nitride thin film was calculated. The effect of pressure on the microstructure of aluminum nitride thin films deposited by magnetron sputtering was investigated. Results The aluminum nitride thin films were mainly textured along (100) direction under different pressures. The intensity of (100) plane diffraction peak became stronger when the pressure increased to 0. 7 Pa, then became weaker when the pressure exceeded 0. 7 Pa, and the intensity of (002) plane diffraction peak was stronger when the pressure was below 0. 6 Pa than that at higher than 0. 6 Pa. The RMS roughness values of AlN films deposited at various total gas pressure were below 3 nm and the roughness first increased and then decreased with the increase of gas pressure. The RMS roughness values reached 2. 678 nm at the pressure of 0. 7 Pa. The optical transmittance of AlN film at various total gas pressures was all above 60% . The thin film optical band gap was 5. 4 eV at the pressure of 0. 7 Pa. Conclusion The results showed that high pressure was beneficial to the growth of (100) crystal plane, while low pressure was beneficial to the growth of (002) crystal plane. The intensity of (100) plane diffraction peak reached the maximum at 0. 7 Pa. Along with the increase of gas pressure, the surface roughness increased first and then decreased. The films were direct band gap semiconductor films.