We proposed a type of piezoelectric composites for energy harvesting from low-frequency noise environment. The composites are composed of metallic rings and discs placed on two surfaces of a clamped PVDF film. An equivalent mass-spring model is used to estimate the range of operating frequencies. Acoustic-structure coupled simulation is conducted to calculate electricity generated from PVDF films and the vibration effects of the central discs and the outer rings areanalyzed. Numerical results show that the vibration modes can be tuned by changing the sizes of discs and rings. The first peak in harvested electricity at a lower frequency corresponds to the resonant mode in which the ring and the disc vibrate in unison, while the second peak at a higher frequency is due to the resonant mode in which the larger block (the ring or the disc) vibrates while the other remains almost motionless. The two types of electrodes, namely the S-type and the U-type, are designed according to the two vibration modes. The experimental result shows that the proposed composite with optimal structure parameters can improve the harvesting efficiency more than 100% in the band of 50- 800Hz.