Abstract: In view of problems such as high seed loss rate and impurity rate of district joint harvester, combined with internal and external roller rotary granulation device, test platform for granulation removal was set up, and simulation analysis results showed that selection device met screening requirements．Impurity content and loss rate in detached grain were used as experimental indexes．Air turbine speed and vibration sieve crank speed, which had a great influence on clearance performance, were selected as test factors．Single-factor test was carried out respectively．When fan speed was 1000 r/min, impurity content and loss rate were 0.65% and 1.06% respectively．When crank speed of vibrating screen was 275 r/min, impurity content and loss rate were 0.55% and 0.87% respectively．Finally, response surface test was carried out by Central Composite design method to study influence of factor interaction on test index．The best matching parameters obtained by test results were fan speed of 900 r/min and vibration sieve crank speed of 300 r/min．Under the best parameter combination, the device was tested several times, and average of its impurity rate and loss rate was 0.75% and 0.62%, respectively, indicating that the device could meet clearance performance requirements of cell harvest under this parameter combination．