In this paper, Cu nano-powder was used to reduce CuO nano-powder by hydrogen reduction process, which was prepared by hydrothermal decomposition method taken CuSO4•5H2O and NaOH as raw materials. The reaction conditions of CuO nano-stick were that concentration of CuSO4 liquor was 0.1mol•L-1, concentration of NaOH liquor was 5mol•L-1, dropping speed was 50ml•min-1, pH value of reacting terminal was 12, stirring speed was 1200 r•min-1, reacting temperature was 60°C, reacting time was 30min. The CuO stick longness was 200nm, diameter was 30nm. The reaction conditions of CuO nano-boll were that dropping speed was 50ml•min-1, pH value of reacting terminal was 7, stirring speed 100 r•min-1, reacting temperature was 80°C, reacting time 30min. The diameter of CuO nano-ball was 50~100 nm. The Cu powder was prepared with materials CuO tick by hydrogen reduction in closed circular system. The higher the temperature, the reaction speed is faster. Hydrogen reduction time was 400s in reacting temperature 240°C. The Cu powder’ size was less than 100nm.