A method for manufacturing metal nano particles having a hollow structure is provided. First, a suitable reducing agent is added into a first metal salt solution, and first metal ions are reduced to form first metal nano particles. Next, after the reducing agent is decomposed, a second metal salt solution with a higher reduction potential than that of the first metal is added. Then, the first metal particles are oxidized to form first metal ions when the second metal ions are reduced on the surface of the first metal by electrochemical oxidation reduction reaction, and thus, second metal nano particles having a hollow structure and a larger surface area are obtained. The method is simple and the metal nano particles with uniform particle size are obtained by this method.