The invention relates to a redox flow battery, which comprises a battery stack, a positive liquid storage tank, a positive auxiliary tank, a negative liquid storage tank and a negative auxiliary tank, wherein the top of the positive liquid storage tank and the top of the negative liquid storage tank communicate with the top of the battery stack through a main liquid inlet pipe with a valve separately; the bottom of the positive liquid storage tank and the bottom of the negative liquid storage tank communicate with the bottom of the battery stack through a main liquid outlet pipe with a valve and an infusion pump separately; the maximum liquid levels of the positive auxiliary tank and the negative auxiliary tank are lower than the lowest interface of the battery stack; the positive auxiliary tank and the negative auxiliary tank communicate with the battery stack through an auxiliary liquid inlet pipe with a valve separately; and the positive auxiliary tank and the negative auxiliary tank communicate with the battery stack through an auxiliary liquid outlet pipe with a valve and an infusion pump separately. According to the redox flow battery, the problems of corrosion, self-discharge and the like due to the fact that the stack is soaked in an electrolyte for a long period of time in a horizontal structure are solved; the service life of the redox flow battery is prolonged; and maintenance is convenient.