With　the　development　and　application　of　H.264　standard,　the　technology　of　H.264-based　video　data　security　becomes　increasingly　important.　This　paper　proposes　a　new　selective　encryption　scheme　based　on　H.264,　it　combines　the　AES　OFB　mode　with　the　sign　encryption　algorithm,　and　encrypts　DCs　and　parts　of　ACs　respectively.　This　method　not　only　keeps　advantages　of　former　selective　encryption　algorithms　in　computational　complexity　and　error-propagation　prevention,　but　also　efficiently　make　tip　for　the　deficiency　in　security　and　compression　performance.　Experimental　results　show　that　the　proposed　method　exhibits　low　complexity　and　good　security,　and　it　has　little　effect　on　compression　ratio　and　supports　error-propagation　prevention.　Moreover,　it　is　suitable　for　secure　transmission　of　mobile　multimedia　and　wireless　multimedia　network　based　on　H.264.