Memory　and　reward　have　been　proved　as　effective　mechanisms　for　maintaining　cooperation　among　selfish　individuals.　In　this　article,　this　study　proposes　a　reward　mechanism　based　on　historical　loyalty,　that　is,　an　individual　who　adhere　to　the　cooperation　strategy　for　a　period　of　time　will　get　additional　reward.　Accordingly,　the　reward　for　a　loyal　cooperator　is　undertaken　by　neighboring　defectors　equally.　The　results　on　prisoner＇s　dilemma　game　show　that,　with　appropriate　loyalty　threshold　and　reward　factors,　the　cooperation　level　can　be　greatly　enhanced.　In　addition,　the　time　evolution　of　cooperator　density　and　the　spatial　distribution　of　cooperators　and　defectors　are　also　studied.　©　2020