We report on the preparation of the three dimensional (3D) network structure CuO by rapid and facile engraving method and their application as high rate anode for sodium ion battery. The CuO is rapidly synthesized by in-situ etched and oxidated the specified Cu foils within 15 min. It shows the 3D network architecture with flower-like nanosheets connected by nanowires, which provides the porous structure, short ion diffusion pathway and collaborative electronic transmission. Furthermore, the etched CuO can be directly used as anode for sodium ion battery without polymer additions or conductive agents. The electrodes exhibit excellent electrochemical performance with a high capacity of 680 mAh·g−1 at 50 mA g−1 and a reversible capacity of 280 mAh·g−1 at 1000 mA g−1. In addition, the electrochemical reaction and detail charge/discharge process are carefully explored to discover the conversion reaction routes and the recession reason. Thus, the 3D network structure CuO might open an insight for transition-metal oxides as energy storage materials.