U-Mo microspheres and Al powders were mixed by vertical planetary pot-classifying mixer. The influences of mixing time, mixing speed and filling rate on the mixing degree of mixed powders were studied systematically. The orthogonal experiment is designed to analyze the influence degree of the three factors on the mixing degree. The mixing degree and microstructure were discussed by variation coefficient method and stereomicroscope, respectively. Results show that optimal mixing process parameters: the mixing time of 90min, the mixing speed of 30r/min and the filling rate of 30%. The optimal mixed powders have a mixing degree of 93.6%. Three kinds of mixed factors impacting on the mixing degree have the order: mixing time
