Zero point of airflow velocity which is the heart of eddy current was found by drawing equal lines and measuring wind speed values of multipoint with digital screen anemometer on the DFQX〖CD*2〗3 material clearing and simulation test platform. Based on analyzing the effect of eddy current by the speed or angle of the centrifugal fan, both the law of the centre of eddy current was affected by changing the angle of the centrifugal fan at the same speed of the centrifugal fan and the centre of eddy current was also affected by changing the speed of the centrifugal fan at the same angle of the centrifugal fan. The results of grain cleaning test showed that the cleaning rate and lose rate were affected by changing the centre of the centrifugal fan. The best results of cleaning grain were that the speed and angle of eddy current were 950r/min and 25°, respectively.