In order to quickly and effectively destroy the powder arch formed above the outlet of the hopper, a convergentdivergent nozzle which could form a high speed air jet was designed. The influence of nozzle structure parameters on air jet velocity was analyzed by using CFD simulation and orthogonal test. The nozzle with conical degree of 60°, throat diameter of 2 mm and inlet diameter of 12 mm was selected. The test results are in good agreement with the numerical simulation results, and the average relative error is 48%. It is proved by experiments that the air jet can break the arch effectively and quickly. The jet penetration region simulated by Fluent is the same as experimental result. The process mechanism of air jet penetrating the powder is revealed, which can provide theoretical guidance for reasonable layout of jet nozzle to break arch.