Abstract: The mechanical structure and adjustability of air valve are the key factors for controlling the separation process.Through the analysis and comparison the features and function for different air valve,and based on the experiments form theoretical study and production practice in many years,designed the new double cover plate valve.This valve with the features of no positive pressure,no back pressure,no wear,no hard impact,open and close easily and quickly,low in air consumption and reliable sealing,which fully reflect the advantages of numerical control technology,making the free adjustment of jigging system in certain range is possible,so that the jigging process can meet the requirement of different coal quality.