Abstract: Three dimensional machining using micro abrasive waterjet was experimentally studied. A specially designed cutting head for micro abrasive waterjet, in which the inside diameter of orifice and focusing tube is 127mm and 300mm respectively, while the average diam eter of silicon carbide solid abrasives is 25μm, was used during experments. An auger mechanisn was used to feed the micro abrasives to mixing chamber of cutting head directly. Then the micro abrasives were mixed with water and accelerated by waterjet in focusing tube, thereafter the micro abrsive waterjet was generated. The auger mechanism was driven by an electrical step motor. Therefore the flow rate of abrasives can be precisely controlled by regulating the rotating speed of the electrical step motor. The cutting head was then mounted on a numeric controlled machine tool with four axes. Thus the three dimensional machining can be experimented. It was shown that the cutting energy of micro abrasive waterjet could be well con trolled by regulating the flow rate ofmicro abrasives. For a given material, if the feed rate of micro abrasive waterjet was kept unchanged, then the cutting depth of the material varied with the flow rate of micro abrasives. Consequently, three dimensional mach ining was realized Micro abrasive waterjet has a wide application in fabrication of sem iconductor, manufacturing of micro mechatronic system as well as optic devices etc.