ZnO films used in film bulk acoustic resonator (FBAR) were deposited o n the aluminum bottom electrode layers by radio frequency magnetron sputtering,and how the spu ttering power influences the preferred orientation,piezoelectric response and polarity distri bution of the prepared films is investigated.X-ray diffraction (XRD) measurements indicate that in a certain range,increasing the sputtering power is conducive to the improvement of crystal quality and c-a xis orientation,and meanwhile,we also observe a decline in the c-axis orientation of the film dep osited at too much higher sputtering power.Simultaneous imaging of the surface topography,as well as the amplitude and phase of the piezoelectric response is performed by piezoresponse force microscopy (PF M),and the results show that the sputtering power has great influence on the piezoelectric activiti es and polarization orientation of ZnO films.The majority of the grains within the prepared films h as upward spontaneous polarization orientation,indicating that the top surfaces of the films are mainly O terminated.The amplitude of the out-of-plane piezeresponse depends on th e crystal quality and preferred orientation of the films.The film deposited at the sputtering power o f 150W exhibits better O-polarity uniformity and greater piezeresponse amplitude in the direction perp endicular to the film surface than those of the other samples.