Abstract: The discretization of continuous numerical attributes is an important step for the application of granular computing．Some current discretization algorithms are classified and discussed．The concept of section granular is proposed．Entropy theory is introduced to define the granularity of section granular．The discretization algorithm based on granular computing is proposed．This algorithm is applied to intrusion detection．The experimental results show that this algorithm is simple and effective,It can assure the accuracy of intrusion detection．

Key words: Granular computing,Section granular,Discretization,Entropy