Aiming at the problem that large fluctuation range of the screening performance of the pneumatic cylindrical sieve membrane impurity separator, additional migration device and reset the layout and size of cylindrical screen holes to maintain the uniformity of airflow distribution, improve the trafficability of impurities，and improve the screening performance stability of the pneumatic cylinder sieve film impurity separator. Based on the analysis of the movement of the membrane hybrid mixture in the cylindrical sieve, the rotational speed of cylinder sieve, wind speed of inlet pipe, and inclination of airflow were selected as test factors. The impurity rate in the film and the film content in the impurity were used as evaluation indexes. A threefactor and threelevel test was designed in principle to analyze the influence of each factor on the quality of the membrane impurity separation operation. The test results showed that the order of influence on the impurity content in the film was: air inlet pipe speed, rotational speed of cylinder sieve and air flow angle; the order of influence on impurity content in the film was: cylinder screen speed, air inlet pipe speed and air flow angle. The comprehensive effects of various factors on the response index were analyzed by using DesignExpert software surface response diagram, which showed that the optimal rotating speed of cylinder sieve, wind speed of the inlet pipe and the inclination of the airflow were 23.8r/min, 5.9m/s and 2.7°, respectively, the theoretical minimum impurity rate in the film and the film content in the impurity for the optimal design were 10.60% and 0.133%, respectively. Then the secondary test was performed to verify the obtained optimal values. It was found that the impurity rate in the film and the film content in the impurity for the optimal design were 10.54% and 0.132%, respectively. The results indicated that the optimization scheme of the device was feasible.