Abstract: To decrease cleaning loss of foxtail millet combine harvest, air and screen cleaning device of millet harvester were analyzed by experiments． With airflow velocity, airflow direction, screening amplitude and crank speed as test factors, and kernel loss rate and impurity rate as test indicators, a cleaning test was conducted on threshed matter from air and screen foxtail millet cleaning device with adjustable parameters． Experimental results showed that kernel loss rate was increasing with increase of airflow velocity, vibrating amplitude and crank speed, and kernel loss rate showed trend of firstly increasing, then decreasing and then increasing with increase of airflow direction angle． Impurity rate was decreasing with increase of airflow velocity, vibrating amplitude and crank speed, and impurity rate showed trend of firstly decreasing, then increasing and then decreasing with increase of airflow direction angle． Optimal cleaning working parameters were recorded as that airflow velocity 4.19 m/s, airflow direction 30.3°, vibrating amplitude 22 mm, and crank speed 218 r/min, and then kernel loss rate was 2.02%, impurity rate was 8.01%． This research can provide reference for design on structure and working parameters of cleaning device for foxtail millet combine harvester．