Abstract: The structure, principle, technical characteristics and existed problems of traditional gangue blocking device of shearer with large mining height were analyzed, an improvement design was proposed and simulation analysis was given. By means of increasing cylinder number, strengthening and thickening top guard, changing rigid connection to flexible connection and adding flow dividing and combining valves, dynamic adjustment and bracing of the guard are achieved, and reliability of gangue blocking device and mining efficiency of shearer are both improved. The simulation result shows that the force of the improved gangue blocking device is more even, and the guard can withstand greater force.