The invention provides a preparation method of a c-axis inclined AlN thin film with homogeneous buffer layer, which comprises the steps that: generating an uncrystallized AlN thin film buffer layer on a substrate which is made from Si, Mo, Pt and Au or combination thereof by means of magnetron sputtering; and generating a c-axis oriented AlN thin film with different inclination degrees by adjusting the deviation angle between the substrate and the center of a target material. The preparation method can overcome the problems that the lattice mismatch between the AlN thin film and the substrate such as Si and GaAs, and the like, is larger, and the control performance of the c-axis inclination degree is worse. When being taken as a piezoelectric layer of a piezoelectric resonance sensor, the AlN thin film generated by the method can reduce the energy consumption of sound wave in liquid and is good for improving the quality factor and the sensitivity of the sensor.