A method for polarizing a piezoelectric film is described. In this method, a piezoelectric film is formed by using an injection deposition method. The piezoelectric film is flat adhered to a surface of a conductive substrate. A polarization process is performed on the piezoelectric film while the piezoelectric film is flat adhered to the surface of the conductive substrate by generating static electricity on the adhesion surface of the piezoelectric film, and generating the static electricity on the adhesion surface of the piezoelectric film comprises using a pressurized gas to blow the adhesion surface, and the adhesion surface of the piezoelectric film is adhered to the even surface of the conductive substrate by an electrostatic adsorption method.