In this paper, flow field inside jet element was simulated with CFD numerical simulation, and the results were analyzed. While with no-load, jet flow attached to and out flowed from one side of the jet element. With different flow to main nozzle, difference of parameters and characteristic of the jet stream is not obvious, so the conclusion is that wall-attached property of jet element is stable with existing structure. This simulation enriched theory of inside flow in jet element and perfected parameter design.