In　order　to　realize　a　trusted　private　network,　firstly,　trusted　computing　technologies　are　utilized.　Then　with　the　use　of　combined　public　key　algorithm　(CPK),　the　trust　chain　from　trustworthy　terminal　can　be　led　into　private　networks,　and　the　USB　Key　technique　is　used　to　overcome　the　weakness　of　CPK.　Finally,　with　the　cryptogram　management　and　security　management　as　the　center,　a　comprehensive　secure　defensive　system　is　constructed,　and　a　trusted　network　model　is　established　to　realize　security,　authenticity,　controllability　and　reliability　of　private　networks.