Aluminum　gallium　nitride　(AlGaN)　thin　films　are　prepared　by　pulsed　laser　deposition　with　different　silicon　doping　concentrations　from　0.5%　to　2%.　The　field　emission　measurement　shows　that　the　1%　Si-doped　AlGaN　film　has　the　best　field　emission　property.　Compared　with　undoped　film,　the　Si-doped　film　has　a　large　emission　current　density　and　a　low　threshold　field.　The　increase　of　doping　concentration　can　increase　the　carrier　concentration,　which　will　add　a　number　of　supply　electrons,　thereby　improving　greatly　the　FE　property　of　AlGaN　film　With　the　doping　concentration　further　increasing,　the　defect　of　film　increases　and　the　electron　mobility　reduces.　The　reduction　of　the　internal　supply　electron　is　greater　than　the　contribution　of　the　increase　of　electrons　concentration,　which　induces　the　field　emission　performance　to　deteriorate.　This　study　will　provide　a　reliable　basis　for　designing　high-performance　field　emission　devices.