Abstract: The flow field in the separation area of the dynamic separator with static guide cascade was measured by angular displacement sensor and endoscope head based on PIV technology.The airflow shows a strong turbulent rotational flow in the annular region outside static cascade,and the impellerspeed has little effect on the flow field in this area.The airflow presents a vortex flow in the stator blade,the vortex center position moves backward gradually with the increase of impeller rotate speed.The lower the regional position is,the closer the vortex center is to the leeward of the blade,and the longer the vortex is.In the region between the static cascade and the impeller,the airflow rotates with the impeller,and the higher the impeller speed of impeller,the stronger the airflow rotates.In the rotor blade,the airflow flows evenly along the runner,and the angle between the flow direction of the airflow and the blade increases with the increase of impeller speed.The gas-solid separation in the dynamic separator is divided into three stages,the first stage is the centrifugal separation in the annular region outside the static cascade,the separation effect of this stage is hardly affected by the impeller speed,the second stage is the vortex separation and impact separation in the static blade,and the third stage separation occurs in the impeller inlet area,which includes centrifugal separation and impact separation.The impeller speed has a great influence on the separation of the latter two stages.