Abstract: Wood chips are the trace evidence in various criminal and traffic accident cases. Because of their complex chemical composition, and because the difference among their indissoluble macromolecular componeats is indistinctive no effective identification method has been established. In this paper, PY-GC/MS technology has been adopted to analyze different kinds of wood chips. The results showed that total ion current chromatograms of different wood chips are simila, i. e,there are a group of characteristic components in every total ion current chromatograms of indissoluble componeats of wood chips, but there are differences among the individual components.