Barrel plating is a method of coating small parts using a horizontal type barrel, which can be operated automatically. Nevertheless, barrel plating for a plating material with a complex geometry has a problem with deviations in the coating thickness due to the supply of the plating solution through the barrel and irregular contact of the plating material and cathode. Therefore, this study examined the relationship between the barrel pore size, number of pores and open pore ratio in copper cyanide barrel plating as well as the plating characteristics in accordance with the process variables, such as the barrel rotation speed, plating temperature, plating voltage and plating time. An automobile wheel nut was selected as the plating material and barrel plating was carried out in a 4.7 L sized barrel. The optimal part charging quantity was found to be 40 ea., and the plating characteristics of the best quality for the optimal plating conditions of the barrel plating process were a plating temperature, plating voltage and rotation speed of 323 K, 1 V and 1.5 rpm in a barrel with 22.5% of open pore ratio.