本文介绍了知识库更新的基本概念及命题知识库更新的复杂性研究现状．近年来，提出了许多方法进行命题知识库的更新，一类是基于公式的方法，一类是基于模型的方法，但所有这些方法在通常情况下都是难解的．本文结合实际应用，提出了一种特殊情况下的多项式时间更新方法，并在ＣＲＥＷＰＲＡＭ上给出了相应的并行算法． This paper introduces the basic concepts of knowledge base updating and the status quo of research on the complexity of knowledge updating. In recent years, many methods have been proposed to update the propositional knowledge base, one based on the formula-based method and one on the model-based method, but all of these methods are usually difficult to solve. In this paper, we propose a polynomial time update method in special cases, and give the corresponding parallel algorithm in CREWPRAM.