Abstract: Except for the integrated charge transferred, the effective area of discharge electrode and pollution of discharge spatters on insulator shell are major limiting factors to the gas spark switch lifetime. After theoretic analysis, increasing electrode area with uniform discharge can improve switch lifetime effectively. We have designed a new three-coaxial-electrodes structure, whose electric field simulation results show nice uniformity in both charging state and triggering state. Meanwhile, a circulative gas path can control the splash direction of discharge spatters to reduce the pollution of insulators inner wall, and enhance the gas insulation recoverability to prolong switchs lifetime. We have carried out the experiments under the repetitive condition (40 kV/20 kA/0.1 Hz). Result shows that this long-lifetime gas spark switch works stably, whose self-breakdown voltage characteristic and trigger delay jitter characteristic are both as good as expected, and single switch has worked more than 13.7105 shots.