Abstract: The process of electroless copper plating on Si was studied.The influences of formaldehyde content, pH, temperature on reaction time of copper electroless plating as well as the micro-morphology and structure of the deposit were analyzed.The results show that with increasing pH value, bath temperature and formaldehyde content, the reaction time is shortened and the plating rate is accelerated.The optimal conditions of the electroless copper plating process were obtained as temperature of 60~72ml/L of HCHO, pH value of 12~12.5 and temperature of 60℃.The surface of deposited coating is uniform.There are not Cu₂O existing in the deposit.