The invention discloses a method for reducing and even eliminating the leakage current of an all vanadium flow energy storage battery system, characterized by making equal voltage points of voltage on electrolyte public pipelines to reduce or even eliminate the leakage current caused by the public pipelines connected with a battery module. The method can be designed flexibly, at the requests of the voltage required by all vanadium flow energy storage battery system and the reduction of system complexity, a small amount of the leakage current can be produced in the tolerable range of the system. Compared with traditional battery system connection types, the influence to the battery system caused by the leakage current can be obviously reduced. The method is especially suitable for the reduction of the leakage current caused by the all vanadium flow energy storage battery system comprising a plurality of subsystems, and is beneficial for raising the current efficiency of the battery system.