A megavolt low jitter multistage corona switch comprises a knife structure electrode 1, a plate electrode 2, a first insulator 3, a screw 4 and a second insulator 5. The corona switch comprises multi-stage corona intervals which employ knife-board structure; the electrode of each corona interval is adjustable; and sulfur hexafluoride gas is supplied to the corona switch. When the switch works, one-stage corona interval is preferentially broken down, and other corona intervals are broken down in the overvoltage. Because the structure of each-stage corona interval is the same, the breakdown voltage of each corona interval is the same. The structure with the same corona interval cascading ensures the low breakdown voltage jitter, reduces the electric field enhancement coefficient, improves the breakdown voltage of the corona intervals and ensures that the corona intervals of overvoltage breakdown have enough high undervoltage rate so as to obtain fast output pulse front edge.