On basis of the approximate similitude criteia for gas-solid two phase flow some experimental set-ups for rotary classiflers are established. According to the similarity principles

model tests on the performance of rotary classifiers with threedifferent structure rotors are completed respectively. Rules for design and process control of the rotaty classifier are developed based on the test results. It is shown that the classifier Performes very well and can obtain stable pulverized coal fineness when the loading is changed.