An electric valve and a control method therefor are disclosed. The electric valve comprises a mechanical valve body, a motor (1), a valve switch state detection apparatus, a control line (9) and a control circuit (80). The motor and the mechanical valve body are in transmission connection; the control line is electrically connected to the control circuit; the control circuit comprises a drive module (2) and a power supply module (5); and the motor, the valve switch state detection apparatus and the power supply module are respectively connected to the drive module. The control circuit further comprises a backup power supply (90) electrically connected thereto. Besides a power supply module which supplies power from the outside, the electric valve is additionally provided with a backup power supply; and after the power supply module has powered down, the backup power supply, in combination with a control circuit, can provide an operation power for the drive module and motor of the electric valve, thus automatically controlling the closing of the mechanical valve body.