The invention discloses a precisely adjustable dielectric barrier discharge device and method thereof, comprising a discharge chamber enclosed by an upper cover, a chamber cylinder and a bottom plate,wherein two discharge electrodes are arranged in the discharge chamber, and the adjustment of the discharge gap between the two discharge electrodes is realized by a translation unit. The upper coveris detachably connected with the cavity barrel to realize the fixed connection and quick disassembly between the upper cover and the cavity barrel. An upper cover, a chamber cylinder and a bottom plate can be firmly connected together, thereby enclosing a closed discharge chamber. The upper cover, the cavity barrel and the bottom plate are easy to disassemble to facilitate the replacement of thefirst and second electrodes. The distance between the first electrode and the second electrode can be changed by the electric cylinder, and the distance between the first electrode and the second electrode increases or decreases by 0.5 mm every time the electric cylinder moves, and the adjustment precision is high, so it is convenient to study the gas discharge.