The invention discloses a switch control method of a discharge device. The discharge device includes primary and secondary discharge channels. The switch of the primary discharge channel includes a primary mechanical switch and a first solid-state switch. The switch of each secondary discharge channel includes a secondary mechanical switch and a second solid-state switch. The method includes the following steps: determining whether there is an over-current in the discharge device during discharging; if there is no over-current in the discharge device, monitoring whether the fault state of a fault branch has been released; if the fault state of the fault branch has been released, after a breaking signal and a conducting signal are sent to the secondary mechanical switch and the second solid-state switch in each secondary discharge channel, making the second solid-state switch in the channel opened; and when the switches in all the secondary discharge channels are turned off, making themain mechanical switch turned off and the first solid-state switch turned on, and then, making the first solid-state switch turned off. Because different control strategies are used for switch controlwhen the switches of the primary and secondary discharge channels are disconnected successively, the mechanical switches are prevented from generating arcs, and the discharge device can be quickly switched off.