To　solve　the　problem　of　information　asymmetry　in　third-party　governance　of　environmental　pollution　under　the　background　of　fuzzy　attribution　of　environmental　responsibility,　the　tripartite　evolutionary　game　model　of　polluting　enterprise,　third-party　governance　enterprise　and　local　government　was　constructed　by　introducing　the　mechanism　of　incentive　policy　system　on　the　strategic　choice　of　parties　and　assessing　the　basic　conditions　for　the　system　to　achieve　evolutionary　stable　state　in　different　situations.　Then,　the　scientificity　of　the　game　subject　and　system　evolution　stability　analysis　is　verified　with　numerical　simulation.　The　study　indicates　that,　setting　a　reasonable　amount　of　rewards　and　punishments　and　their　distribution　ratio,　enhancing　the　reputational　benefits　of　both　enterprises,　and　controlling　the　cost　of　local　government　supervision　are　the　key　factors　that　affect　the　strategies　choice　of　the　three-parties.　The　reward　and　punishment　distribution　incentive　mechanism　designed　according　to　the　“responsibility　sharing　principle”　demonstrates　its　effectiveness　in　promoting　the　trust　and　cooperation　between　the　principal　and　agent;　and　the　polluting　enterprise　shows　stronger　income　sensitivity　than　the　third-party　governance　enterprise　does.　To　this　end,　the　main　responsibility　status　of　polluting　enterprise　needs　to　be　implemented,　and　the　proportion　of　rewards　and　punishments　shall　be　increased　as　much　as　possible.　©　2023　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.