The invention discloses an energy storage converter, and the energy storage converter comprises a control circuit; and a divider resistor, a first switch circuit and a second switch circuit, which areall arranged between an AC side and a DC side. After an non-activation signal of a flow battery is received, the control circuit controls the first switch circuit to be switched on and the second switch circuit to be switched off, and the AC side is electrically connected with the DC side through the divider resistor and the first switch circuit; and after an activation signal of the flow batteryis received, the control circuit controls the first switch circuit to be disconnected and the second switch circuit to be switched on, and the AC side is electrically connected with the DC side through the second switch circuit. In the initial state of the flow battery, the divider resistor can be connected to a circuit to adjust the current of the DC side; when the voltage of the flow battery reaches a preset value, the pre-charging of the flow battery is realized to activate electrolyte, the pre-charging is finished, the energy storage converter can normally control the flow battery to carry out charging and discharging circulation, and the automatic switching between the pre-charging and the normal charging and discharging of the flow battery is realized.