Abstract: An effective way to program’s analysis is program slicing which, according to a given slicing criterion, extracts the necessary part of a program for analyzing, such as program debugging, program testing, program refactoring and etc. Slicing technique has been successfully applied in structural programs. But to object-oriented programs, many problems would still occur when traditional slicing techniques are applied. ISDG, an improved system dependence graph, is proposed in order to better describe relationships in object-oriented programs. ISDG solves the description problem of parameterized objects. Moreover, a novel slicing criterion and related slicing algorithm based on ISDG are presented.