Air cannon is a kind of de-clogging device which produces impulse force by instantly releasing the compressed air deposited in a pressure vessel.Air cannons are widely used in the transport pipes of warehouses,docks,furnaces and coal mines.In this paper,the theoretical analysis with isentropic flow hypothesis is firstly conducted on a simplified model to deduce the theoretical maximum of impulse force.And numerical study is carried out to predict the steady and unsteady impulse forces via simulating the whole exhausting process of the air cannon.The results demonstrate that the impulse force can be improved via increasing the piston sleeve inlet length and increasing the nozzle diameter.Laval nozzle can also increase the impulse force of the air without increasing the air mass flow.The optimization of the air cannon is then conducted on the basis of the theoretical and numerical analyses.Experimental measurements indicate that the computations well simulate the working process of the air cannon and the impulse force of the optimized design is 50%higher than the original model.For the cases with working pressure of 0.8 MPa,the optimized design is 60%higher than the original one. Air cannon is a kind of de-clogging device which produces impulse force by instantly released the compressed air deposited in a pressure vessel. Air cannons are widely used in the transport pipes of warehouses, docks, furnaces and coal mines. In this paper, the theoretical analysis with isentropic flow hypothesis is pre admitted on a simplified model to deduce the theoretical maximum of impulse force .And numerical study is carried out to predict the steady and unsteady impulse forces via simulating the whole exhausting process of the air cannon. that the impulse force can be improved via increasing piston collar inlet length and increasing the nozzle diameter. Laval nozzle can also increase the impulse force of the air without increasing the air mass flow. The optimization of the air cannon is then conducted on the basis of the theoretical and numerical analyzes. Experimental measurements indicate that the computations well simulate the working process of the a ir cannon and the impulse force of the optimized design is 50% higher than the original model. For the cases with working pressure of 0.8 MPa, the optimized design is 60% higher than the original one.