In the traditional system, for some indigenous error in the measurement and trajectory track, the precision of trajectory parameters is not enough high so that it often results in some false alarms for the safety of rockets. After analyzing some main characteristics and disadvantages of existing systems for the safety rockets, a new idea and technology based on the intelligent decision and reasoning on more accurate, extensible and flexible safety knowledge are adopted. In the process of achieving this system , a function based on the immune theory is discussed and used in dealing, acquiring and optimizing safety knowledge needed, and a design idea, a system framework and a method applied for the realization of this knowledge-based intelligent decision making system are also proposed to improve the certainty and authenticity of a safety decision.