A reducing agent supplying device for a vehicle SCR system, comprising: a tank configured for storing a reducing agent; a pump connected with the tank via a suction line; an injecting assembly connected with the pump via a pressure line and equipped with a metering valve; characterized in that the reducing agent supplying device further comprises: a power accumulator disposed in the pressure line between the pump and the injecting assembly, wherein the power accumulator comprises a casing, a completely or partially movable partition member dividing an inner volume of the casing into an upstream chamber and a downstream chamber, an elastic member biasing the partition member towards the upstream chamber, and valve means disposed in the partition member, the valve means being able to allow the reducing agent in the upstream chamber to flow into the downstream chamber in a particulate position of the valve means; a backflow element disposed between the upstream chamber of the power accumulator and the suction line; wherein when the pump is turned on, the reducing agent is fed into the upstream chamber by the pump, and the reducing agent in the upstream chamber overcomes the elastic force of the elastic member and forces the complete or a part of the partition member to move towards the downstream chamber, during which movement the valve means is opened, and thus the reducing agent is allowed to flow through the upstream chamber into the downstream chamber so that the reducing agent is fed to the injecting assembly through the pressure line; and when the pump is turned off, the partition member is driven by the elastic member so that the complete or a part of it moves towards the upstream chamber, as a result of which the reducing agent in the pressure line and the injecting assembly is drawn into the downstream chamber, and at least a part of the reducing agent in the upstream chamber flows back to the suction line or the tank through the backflow element. a tank configured for storing a reducing agent; a pump connected with the tank via a suction line; an injecting assembly connected with the pump via a pressure line and equipped with a metering valve; characterized in that the reducing agent supplying device further comprises: a power accumulator disposed in the pressure line between the pump and the injecting assembly, wherein the power accumulator comprises a casing, a completely or partially movable partition member dividing an inner volume of the casing into an upstream chamber and a downstream chamber, an elastic member biasing the partition member towards the upstream chamber, and valve means disposed in the partition member, the valve means being able to allow the reducing agent in the upstream chamber to flow into the downstream chamber in a particulate position of the valve means; a backflow element disposed between the upstream chamber of the power accumulator and the suction line; wherein when the pump is turned on, the reducing agent is fed into the upstream chamber by the pump, and the reducing agent in the upstream chamber overcomes the elastic force of the elastic member and forces the complete or a part of the partition member to move towards the downstream chamber, during which movement the valve means is opened, and thus the reducing agent is allowed to flow through the upstream chamber into the downstream chamber so that the reducing agent is fed to the injecting assembly through the pressure line; and when the pump is turned off, the partition member is driven by the elastic member so that the complete or a part of it moves towards the upstream chamber, as a result of which the reducing agent in the pressure line and the injecting assembly is drawn into the downstream chamber, and at least a part of the reducing agent in the upstream chamber flows back to the suction line or the tank through the backflow element. a power accumulator disposed in the pressure line between the pump and the injecting assembly, wherein the power accumulator comprises a casing, a completely or partially movable partition member dividing an inner volume of the casing into an upstream chamber and a downstream chamber, an elastic member biasing the partition member towards the upstream chamber, and valve means disposed in the partition member, the valve means being able to allow the reducing agent in the upstream chamber to flow into the downstream chamber in a particulate position of the valve means; a backflow element disposed between the upstream chamber of the power accumulator and the suction line; wherein when the pump is turned on, the reducing agent is fed into the upstream chamber by the pump, and the reducing agent in the upstream chamber overcomes the elastic force of the elastic member and forces the complete or a part of the partition member to move towards the downstream chamber, during which movement the valve means is opened, and thus the reducing agent is allowed to flow through the upstream chamber into the downstream chamber so that the reducing agent is fed to the injecting assembly through the pressure line; and when the pump is turned off, the partition member is driven by the elastic member so that the complete or a part of it moves towards the upstream chamber, as a result of which the reducing agent in the pressure line and the injecting assembly is drawn into the downstream chamber, and at least a part of the reducing agent in the upstream chamber flows back to the suction line or the tank through the backflow element.