Task　allocation　is　an　important　issue　in　wireless　sensor　networks　(WSNs),　and　the　existing　traditional　solutions　to　this　problem　in　high-performance　computing　cannot　be　directly　implemented　in　WSNs　because　of　limitations　such　as　resource　availability　and　shared　communication　medium.　In　this　paper,　we　address　the　task　allocation　problem　for　a　heterogeneous　WSN,　and　a　trust　dynamic　task　allocation　algorithm　is　proposed.　Firstly,　to　ensure　the　nodes　in　the　same　coalition　are　mutually　closer　in　distance,　a　discrete　particle　swarm　optimization　(PSO)　is　designed　to　generate　a　structure　of　the　parallel　coalitions.　Secondly,　in　order　to　minimize　the　execution　time　of　the　tasks,　save　the　energy　cost　of　the　nodes　and　balance　the　load　of　the　network,　we　design　task　strategies　and　payoff　functions　by　invoking　the　game　theory　in　WSNs　and　propose　a　PSO　with　the　redesigned　fitness　function　to　find　the　Nash　equilibrium　point　for　the　purpose　of　improving　the　effectiveness　of　scheduling　and　the　reliability　of　the　network.　In　this　step,　the　sink　node　will　play　the　role　of　trust　manager,　and　it　will　allocate　tasks　based　on　the　Nash　equilibrium　point,　which　is　a　trust　solution　to　make　sure　all　tasks　can　be　finished.　Finally,　the　extensive　experiments　are　conducted　to　compare　our　algorithm　with　two　other　algorithms.　The　experimental　results　show　the　feasibility　and　effectiveness　of　our　algorithm,　which　can　obtain　a　good　balance　between　local　solution　and　global　exploration　and　achieve　superior　energy　efficiency　and　network　reliability　within　a　short　period.　©　2014　John　Wiley　&　Sons,　Ltd.