Accurate 3D flow characterization in a microchannel is becoming increasingly important for the design and development of microfluidic chips. In recent years, a light held camera that can simultaneously record the direction and position information of rays in a single photographic exposure has been developed and employed in the held of computer graphics. In this paper, a microparticle image velocimetry based on light held imaging (light held μPIV) is proposed to reconstruct the 3D velocity held of a microscale flow. Both simulations and experiments are performed to verify the proposed method. The light held image of tracer particles and the point spread function (PSF) of a light held microscopic imaging system are numerically calculated based on the Abbe imaging principle. The 3D positions of the tracer particles in a flow held are then reconstructed by the Lucy-Richardson 3D deconvolution algorithm. Furthermore, a light held μPIV system based on an assembled cage light held camera with a microscope is developed, and calibrations are performed to obtain the geometric parameters of the μPIV system accurately. The simulation and experimental results demonstrate the feasibility of the proposed light held μPIV. Compared with the synthetic refocusing reconstruction method, the Lucy-Richardson 3D deconvolution algorithm greatly improves the lateral and the axial resolutions of the flow held.