Single crystal nickelbased superalloy DD98 was taken as the research object,and a micromilling platform for micro quantity lubrication cooling system was built.The effect mechanism and rule of micromilling process parameters on surface roughness under micro lubrication and dry cutting cooling were compared.The results show that the surface roughness of single crystal superalloy is improved greatly under the condition of micro lubrication cooling;under two different cooling conditions,the surface roughness of micromilling decreases with the increase of spindle speed,increases slowly with the increase of feed speed after overcoming the scale effect,and increases with the increase of cutting depth.