We　provide　a　network　game　to　analyze　the　innovation　network　structure　by　incorporating　endogenous　R&D　spillovers　and　diffusion　effects,　reconciling　the　limited　types　of　innovation　alliance　in　practice.　In　our　network　model,　enterprises　can　actively　choose　to　invest　in　R&D　or　establish　links　with　others　to　absorb　R&D　spillovers.　We　characterize　the　network　structure　of　enterprises＇　strategic　R&D　decisions　in　different　types　of　spatial　equilibrium.　We　further　extend　the　theoretical　framework　to　generate　industry-specific　implications　under　cooperative　R&D,　location　choice,　spatial　agglomeration,　and　social　capital　allocation　in　innovation　networks.