Abstract: Spray drying experiments of the lipuid extracts from cups of Quercus spp. and bark of Larix gemelini were designed by the cross experiment method. By means of a small centrifugal spray drier, all samples of the two powder extracts were prepared under definite conditions. Accumulative subsidence curves of all powder extract samples were drawn following the determining of their sizes by an automatic record subsidency balance. Based on the Stocks law and the regression formulae from the accumulative subsidence curves, a program was made and the sizes, distributive functions, percentage of contents and volume-area average diameters of all powder extract samples were calculated in a micro-computer. Results showed that particle diameters of the two powder extracts were less than 344 microns, their volume-area average diamters ranged from 21 to 36 microns, and the particle diameters corresponding to the highest points of the distribution curves of all powder extract samples ranged from 14 to 44 microns, with a content percentage of 71-75%. The rotary speed of the centrifugal atomizer was the main factor to influence the particle diameters of the two powder extracts. With the increase of the rotary speed of the centrifugal atomizer, the particle diameters of the two powder extracts soon became smaller. The inlet temperature of heated air, the feed temperature and concentration were secondary factors influencing their particle diameters, of which the inlet temperature of heated air exerted cardinal influence on the particle diameters of the powder extracts of the cups from Quercus spp. The particles rapidly became smaller in diameter with the increase of the inlet temperature of heated air.