Abstract: Software defects are the root causes that lead software unreliable, thus the reduction of software defects is the key way to improve software reliability. How to improve the software reliability using the defect data accumulated? In this paper, the definition of software defect pattern was addressed on the basis of the concept of software defect and pattern. Through analyzing the defect data accumulated, the classification of defect patterns was proposed. The defect patterns in software requirement analysis, design and coding phase were advanced. How to apply the defect patterns is claborated in the process of software development and testing, which provides idea on how to improve software reliability utilining defect data.

Key words: Software defect, Pattern, Defect pattern, Defect pattern database