Abstract: By introducing the concept of information quantity and knowledge granularity to ordered information system，several properties and theorems are gained.In the process of attribute reduction，the author proves that the information quantity is monotone decreasing.Using information quantity to defined the significance of attribute.With the significance of attribute as heuristic information，a heuristic algorithm based on information quantity for reduction of attribute is presented.The time complexity of this algorithm is O（|A|³|U|²）.Finally，the experimental results show that this algorithm can find the reduction of an ordered information system.

摘要： 在序信息系统中引入了知识的信息量和知识粒度的概念，得到了它们的若干性质和定理。证明了在知识约简过程中，信息量的变化趋势是递减的；利用信息量的概念，定义了属性的重要性，并以属性重要性作为启发信息，提出了一种基于信息量的属性约简启发式算法，该算法的时间复杂度为O（|A|³|U|²）；最后通过例子说明，该算法能得到序信息系统的一个约简。