The invention discloses a hydro-thermal synthesis method of a copper oxide nanometer rod, which belongs to the field of inorganic non-metal materials, and comprises the steps: soluble copper salt such as copper sulphate is dissolved in water and added with an appropriate amount of different auxiliaries to be taken as a composite template agent, NaOH solution is used for regulating the pH value tobe 12-14, and precipitate and the solution are heated in a high-pressure autoclave for the growth of the nanometer copper oxide. The heating mode can be microwave heating or resistance wire heating, and copper oxide nanometer rods grow in the solution. The method has the advantages of simple technology and low cost, and uses the composite template agent for controlling the appearance and the sizeof the copper oxide nanometer rod.