For　the　NAT　gateway　widely　used　in　the　computer　network,　PC　can　not　connect　to　another　one　through　NAT　gateway　using　TCP　directly.　Despite　there　are　many　methods　like　UPNP　and　Port　prediction　which　can　resolve　the　problems,　it　is　difficult　to　be　used　for　the　Low　penetration　rate.　In　this　article,　we　design　TT-STUN　protocol　using　TCP　To　Stun　To　TCP＇s　design　for　effective　TCP　NAT　traversal.　According　to　reliable　data,　its　penetration　can　reach　90%.　©　2010　IEEE.