Abstract: In order to improve the quality of photoacoustic reconstructed image, an algorithm of filter back-projection was adopted. A Q-switched Nd∶YAG laser operating at 1 064nm was used as the light source. The laser had a pulse width of 7ns and a repetition frequency of 20Hz. A needle PVDF hydrophone with a diameter of 1mm was used to detect photoacoustic signals. The photoacoustic reconstructed images of four rounded absorbers and five hairs were obtained. The results of simulations and experiments show that the algorithm restrains noise effectively, and improves the contrast and resolution of images.