Wireless　sensor　actuator　network　(WSAN)　emerges　as　a　potential　technology　with　the　capacities　of　self-organizing　communication　and　feedback　control.　In　this　paper,　we　present　a　novel　collaborative　optimization　algorithm　of　plant　control　and　system　cost　toward　WSANs　taking　time　delay　into　account.　First,　the　WSAN　model　is　formulated　as　a　linear　system　with　multi-path　network　structure.　In　order　to　provide　effective　control　and　reduce　the　usage　of　system　resource,　the　quadratic　cost　function　is　introduced　as　the　collaborative　optimization　problem　in　discrete-time　domain.　Then,　a　two-phase　design　is　proposed　to　derive　the　design　of　optimal　control　for　each　given　path　in　terms　of　a　backward　recursion.　In　addition,　the　best　transmission　path　selection　is　obtained　depending　on　minimal　system　power　consumption.　Finally,　numerical　simulations　are　utilized　to　show　the　effectiveness　of　the　proposed　algorithm　in　both　traditional　control　system　and　load　frequency　control　in　the　power　grid　application.