The invention discloses a planar multi-channel discharge three-electrode coaxial gas spark switch which comprises an organic glass shell and three electrodes, wherein the organic glass shell is formed by the mutual buckling of an upper cover and a lower cover and the three electrodes are arranged in the cavity of the organic glass shell. The gas spark switch is characterized in that an inner electrode, a trigger electrode and an outer electrode are coaxially arranged in the cavity of the organic glass shell sequentially from inside to outside, and the three electrodes are respectively provided with an electrode leading-off rod; the trigger electrode is inserted into the inner electrode and the outer electrode to form a circumferential radial gas discharge clearance, the trigger electrode is inserted in the part of the outer cambered surface of the bottom surface of the inner electrode, which is tangential to the cylindrical surface of the inner electrode; the bottom surface of the trigger electrode is provided with a right angle-shaped edge, and the flat surface in the radial direction of the right angle-shaped edge is a gas discharge plane; and one side of the lower cover is provided with a gas hole for the communication of gas. The gas spark switch can realize multi-channel discharge and conduction, the discharge channels are positioned on one plane, and discharge phenomenoncan be observed. Besides, the gas spark switch has higher ablation resistance.