A uniform electrical field dielectric barrier discharge reactor consists of an electrode unit, a dielectric catalyst container and an insulative housing. Each electrode plate of the electrode unit includes an insulative plane frame structure, and discharge needles evenly distributed on the insulative plane frame structure. The dielectric catalyst container is a hollow solid member internally coated with a metallic catalyst coating layer. The flow directing plate is made of a conducting substrate, having two opposite sides thereof covered by a metallic catalyst coating layer. The invention is practical for use in an air purifier, fluid sterilizer or waste water treatment equipment.