Redundancy control is an important aspect in knowledge organization，management and maintenance．According to the characteristics of SC—grammar and ma—chine translation system，this paper presents a new idea that divides redundant rules intotwo kinds：obvious redundant rules and hidden redundant rules．The paper gives an algo—rithm for finding obvious redundant rules and discusses in detail the basic strategies that rule out some hidden redundant rules reasonably．Some basic principles to control redun—dancy of rule base are given also．