Abstract: Forward slicing and backward slicing are two different slicing techniques.In order to understand the similarities and differences between the two slicing techniques，some experiments are done.Two results are got： one is that the average size of all static backward slices is the same as the average size of all static forward slices； the other is that the distributions of backward slices cluster averagely，while the distributions of forward slices cluster in the extreme.

Key words: program slicing, forward slicing, backward slicing

摘要： 前向切片和后向切片是两种不同的切片技术，为了研究它们之间的异同，通过实验，得到两个结论：后向切片分析的平均缩减率等于前向切片分析的平均缩减率；后向切片分析的缩减率较均衡，前向切片分析的缩减率变化较大，极端情况较多。

关键词: 程序切片, 前向切片, 后向切片