The dust is filtered by the filter bag and left on the outer surface of the filter bag to form a powder layer. When the filter dust reaches a certain thickness or after a certain time, the operation resistance of the filter bag dust collector increases. In order to control the operating resistance within a limited range (generally 1200~1500Pa), the injection control instrument in pulse sends a signal regularly and triggers the opening of the pulse valve one by one in sequence, so that the compressed air of the air division box is sprayed into each filter bag by the blowpipe, resulting in the rapid expansion of the filter bag. Due to the action of air flow, the dust accumulated on the filter bag falls off. After the pulse valve is closed, the reverse air flow is generated again, which makes the filter bag shrink rapidly, forming an expansion and a contraction. The filter bag expands and contracts and jitter, so that the powder accumulated on the outer surface of the filter bag falls off due to the action of inertia and falls into the ash collector at the bottom of the dust collector under the action of gravity.