Based on electrochemical principle, an electrochemical micromachining system is developed and a novel detection theory of process parameters for the electrochemical micromachining is proposed. Based it, process parameters for the electrochemical micromachining are measured which includes electrolyte resistivity and the balance voltage. Besides it, an optimum solution concentration to obtain the best process accuracy of the electrochemical micromachining is determined. The research is useful for determining the process parameters for the electrochemical micromachining.