Today,　with　the　severe　competition,　strategic　alliance　has　already　become　the　main　way　of　cooperation　among　enterprises.　Therefore,　the　evolution　directions　of　strategic　alliance　are　focused　by　many　enterprises.　The　article　based　on　the　theory　of　lifecycle,　analyses　the　different　evolution　directions　between　horizontal　strategic　alliance　and　vertical　strategic　alliance,　and　then　draws　the　conclusion　that　the　vertical　strategic　alliance　has　the　further　probability　to　evolutes　to　the　strategic　network.