Spark gap switch has been widely investigated as important candidates in compact pulsed power systems. In this paper, a high-power corona-stabilized spark gap switch, was investigated to reduce the dispersion of breakdown voltage of the switch. Specially, the electrode structure was designed with elliptical chamfered annular shape to decrease the breakdown voltage dispersion. The field distortion coefficients and field distribution of the switch were studied numerically and analyzed with different structures. Then, the switch was developed and experimentally studied. The results show that as the breakdown voltage varying from 50 kV to 70 kV, approximately, the breakdown voltage dispersion of annular electrode structure were reduced compared with that of planar electrode structure. Under the breakdown voltage of 60 kV, when the repetition frequency is changing from 15 Hz to 25 Hz, approximately, the breakdown voltage dispersion of the annular electrode with corona needle were increased significantly from 0.34% to 0.64%, while all values remain lower than those measured without the corona needle. The results show reasonable agreement with numerical analysis, which meets potential applications including compact and high-power pulsed power systems.