The invention discloses a butterfly valve pneumatic redundant system used for rocket launching water spraying and a control method thereof. A gas tank, a first electromagnetic valve set, a first one-way valve and a pneumatic device in the system are sequentially connected, and a normal-state air supply passage is formed; the gas tank, a second electromagnetic valve set, a second one-way valve and the pneumatic device are sequentially connected, and a fault-state air supply passage is formed; the pneumatic device is connected with a butterfly valve; the method comprises the steps that S1, three-position four-way electromagnetic valves A and C are kept closed, and a three-position four-way electromagnetic valve B is kept opened; S2, whether a three-position four-way electromagnetic valve A is normal or not is detected, if the valve A is normal, the step S3 is executed, and if the valve A is not normal, the step S4 is executed; S3, through the normal-state air supply passage, air is supplied to the pneumatic device; S4, through the fault-state air supply passage, the air is supplied to the pneumatic device. the effective combination and redundant control scheme of the electromagnetic valves can be creatively developed, in-time response of the butterfly valve can be ensured, and reliability of the action of the butterfly valve used for rocket launching water spraying is greatly improved.