H.　264　video　coding　standard　supports　a　broad　range　of　application,　and　how　to　guarantee　its　security　has　already　become　an　urgent　problem.　In　this　paper,　we　propose　a　video　encryption　algorithm　for　H.　264,　which　combines　stream　cipher　algorithm　with　entropy　coding　process.　It　obtains　video　content　security　by　encrypting　codeword　index　to　scramble　the　position　of　the　codeword.　Experiments　show　that,　the　proposed　algorithm　is　able　to　provide　compromise　between　security　and　complexity,　has　little　effect　on　compression　performance.　It＇s　believed　to　be　applied　in　the　fields　of　video　conference,　digital　rights　management,　multimedia　storage,　etc.