Anti-retroactivity has been widely accepted in law-based countries. The principle that procedural law applies retroactively derives from a law proverb saying “substantive law applies prospectively,while procedural law retroactively”. Legal procedures in modern sense not only refer to judicial procedure, but also include legislative, administrative and other forms as well. According to the traditional theory of retroactive effect, procedural law mainly applies to unclosed cases, with technical procedural matters in general, and due procedural matters, substantive matters and adjudged matters as an exception. As to the complexity of cases, more specific work should be done on the retroactive application of procedural law.