Abstract: Additives is the main factor that affect the quality of cathodic copper in the system of electrolytic copper in which the concentration of copper and acid is relatively stable. The condition of cathodic is used to control the amount of additives in the electrolytic copper production process. If the concentration of additives can be determined accurately, it will be useful of controlling and regulating the best concentration of additives and get the tight smooth copper cathodic products in the high current density. This paper introduces the determination methods of the gelatin, thiourea, chloride ion in copper electrolyte and the control-method of the additives by controlling the cathodic over-potential.