In this study, copper oxide (CuO) nanosheet arrays are synthesized on a copper substrate by using the water bath method. The CuO nanosheet arrays formed after a 10-min reaction time exhibit the highest initial discharge specific capacity of 629.1 mA·h·g ^-1and good cycle properties (79.6% retention after 100 cycles). When compared with the traditional bulk copper oxide anode materials, the CuO nanosheet array structure used as the negative electrode material for lithium ion batteries effectively solves the volume expansion during charging. Furthermore, it reduces the diffusion distance of the lithium ion in the CuO crystal, improving the specific capacity and performance of CuO used as the negative electrode materials.