Tetragonal　polycrystalline　Mn-Ga　nanoflakes　with　a　nominal　composition　of　Mn1.33Ga　were　prepared　by　the　surfactant-assisted　high-energy　ball　milling　method,　and　the　effects　of　milling　time　and　annealing　treatment　on　structure　and　the　magnetic　properties　were　also　investigated　in　detail.　The　irregular　Mn1.33Ga　flakes　show　typical　shape　anisotropy　and　a　high　aspect　ratio　with　thicknesses　in　the　range　of　100　nm　similar　to　3　mu　m.　Crystalline　grain　is　reduced　to　10　nm　when　increasing　the　milling　time　above　4　h.　Coercivity　is　greatly　improved,　and　the　highest　coercivity　of　7.2　kOe　is　obtained　for　flakes　milled　for　2　h,　but　the　saturation　magnetization,　M-s,　and　remanence,　M-r,　decrease　sharply　during　the　ball　milling　process.　Medium-temperature　annealing　is　beneficial　to　the　crystallization　and　the　enhancement　of　magnetization.　After　annealing　at　773　K　for　30　min,　M-s　and　M-r　are　recovered　to　68　and　41　emu/g,　respectively;　and　the　(BH)(max)　can　reach　2.3　MGOe　which　is　comparable　with　that　of　2.5　MGOe　for　films　or　microparticles.