The invention discloses an anode assembly used for extra-groove electroplating of an engine cylinder block. The anode assembly comprises an anode body and an anode base fixed and conductively connected to the anode body, and an electroplating liquid backflow channel penetrates the anode body and the anode base. The anode assembly can be suitable for an extra-groove and intra-cavity electroplating scheme with electroplating liquid flowing, a flowing electroplating environment is formed and used for cylinder block electroplating, installation and use are convenient, the flowing electroplating liquid ensures that positive ions on plating are replaced in real time, the concentration difference of positive ions on the surface of cathode plating is basically unchanged, a large concentration difference is avoided, and the thickness change of the plating is controllable. Due to the undifferentiated concentration and the stable and uniform liquidity, density and compactness of the plating is ensured, positive ions not compactly combined with the plating can be brought away by the flowing electroplating liquid, loosened combination is avoided; and meanwhile, burrs on a plated edge can be effectively avoided through the structure, and the electroplating quality is ensured.