In　this　paper,　we　study　the　effect　of　preferential　assistance　on　cooperation　in　the　donation　game.　Cooperators　provide　benefits　to　their　neighbors　at　some　costs.　Defectors　pay　no　cost　and　do　not　distribute　any　benefits.　The　total　contribution　of　a　cooperator　is　fixed　and　he/she　distributes　his/her　contribution　unevenly　to　his/her　neighbors.　Each　individual　is　assigned　a　weight　that　is　the　power　of　its　degree,　where　the　exponent　α　is　an　adjustable　parameter.　The　amount　that　cooperator　i　contributes　to　a　neighbor　j　is　proportional　to　j＇s　weight.　Interestingly,　we　find　that　there　exists　an　optimal　value　of　α　(which　is　positive),　leading　to　the　highest　cooperation　level.　This　phenomenon　indicates　that,　to　enhance　cooperation,　individuals　could　give　high-degree　neighbors　more　help,　but　only　to　a　certain　extent.　©　2018　IOP　Publishing　Ltd　and　SISSA　Medialab　srl.