A three-dimensional particle image velocimetry (PIV) system is introduced in this paper. Based on camera array light field technology and Tomographic PIV principle, this system is designed for the measurement of instantaneous or continuous three-dimensional velocity of the flow field section or for the measurement of instantaneous three-dimensional velocity within a volume. The camera array light field technology is capable of collecting four-dimensional light field data, and can flexibly adjust the observation field of view, focus position and depth of field through calculation processing. Therefore, combining the camera array light field technology with the Tomo-PIV a 3-dimensional PIV system is achieved. In this paper, the design and development of the system is presented, experimental results and analysis based on this system are discussed.