Abstract: The size of tungsten powder which is changed along the conditions of ball mill is determinated by MASTERSIZR-2000 laser analyser, and the effect on the size of tungsten powder of the grinding time and rotating speed is discussed also.The results show that the ultrafine tungstem powder with the size of-5.0μm can be obtained in the conditions which the grinding dense is 40%, the grinding time is 70h, the ratio of materials is 30:1, and the speed of rotation is 750r/min.