Language and law are closely interrelated and their development is co-existent. Forensic linguistics is turning from legislative or judicial verbal system to a much wider scope——the language of legal science. Discourse analysis of legal science is actually to probe into the language structure of spoken or written form beyond word and syntactical levels through linguistic analytical methods. The vague legal discourse analysis in judicial contexts, on the one hand,is specifically characteristic of the persons involved in legal affairs so that, police officers, prosecutors, judges and lawyers may find solid testimony when they cope with and justify both civil and criminal cases and more importantly presents itself as a necessary strategy for helping to realize fairness in legal proceedings and social justice. Learning legal discourse analysis in judicial processes from western countries can enrich our knowledge in jurisprudential research on language of legal science.