Objective To prepare and control Cu/Cu2O composite in only one-step. Methods Crystal morphology and copper content of Cu/Cu2O composite made through the hydrothermal method was controlled by changing reaction time, temperature, usage amount of raw material, proportion of ethyl alcohol and water mixed solution, etc. Results The copper content in Cu/Cu2O composite increased significantly with the adding of ammonium hydroxide and formic acid, but decreased with the adding of copper nitrate and water content in the mixed solution（ethyl alcohol and water）. However, there was no obvious variation in the copper content of Cu/Cu2O composite with changes of reaction temperature and time. Moreover, the morphology of the sample changed from cauliflower shape, regular octahedron, regular octahedron and dodecahedron to near-spherical shape with the increasing of ammonium hydroxide and formic acid, but the changes of morphology were to the contrary with the increasing of copper nitrate and water content in the mixed solution（ethyl alcohol and water）. In addition, the morphology of crystal changed to regular octahedron and generated pores with the increasing of the reaction temperature. Conclusion Cu content and morphology of Cu/Cu2O composite can be regulated successfully by changing the synthesis parameters.