Redundant invariants increase processing time and memory consumption, which make serious effect on the application of invariants. The elimination of invariant redundancy is an important part in the invariant study. Now most methods of invariant redundancy elimination are based on optimization of invariants detecting tool which lack the principles analyse and system solutions of redundant invariants themselves. This paper first analyses the theory about classification and forming reasons of redundant invariant and then discusses the judgement of three kinds of invariant redundancy: equivalent r...