A　real-time　method　for　measuring　the　polarization　state　based　on　birefringence　crystal　wedge　was　proposed　and　it　was　applied　to　analyze　the　polarization　state　of　transmitted　light　from　twist　nematic　liquid　crystal,　the　dynamic　measurement　of　liquid　crystal　molecule　mean　director　was　achieved　by　this　method.　Polarization　interference　method　based　on　crystal　wedge　was　used　to　encode　the　polarization　parameters　of　detected　light　into　two　groups　of　interference　fringes,　real-time　measurement　of　polarization　state　was　realized　through　stripe　position　location.　According　to　the　relationship　between　the　director　angle　of　liquid　crystal　director　and　transmitted　polarization　state,　dynamic　information　of　liquid　crystal　mean　director　can　be　derived.　The　measurement　speed　is　5　time　per　second　in　this　experiment,　and　the　accuracy　of　tilt　and　twist　angle　of　liquid　crystal　average　director　is　0.2　degree.　An　effective　and　valuable　approach　for　rapid　measurement　of　liquid　crystal　molecule　mean　director　is　provided　in　this　work.　©　2016,　Science　Press.　All　right　reserved.