Abstract: A three dimension(3-D)numerical turbulentmodel is used to study the flan characteristics of turbulent jets in crossf low which is characterized as a complex 3-D flow.The turbulent model is solved using the hybrid finiteelement analytic method, and is tested through the experimental data.The turbulent model is then applied to smiulating flow and vorticity fieldswith different diffuser forms and velocity ratios, and the formation and development of vortex structures in these flow conditions are obtained.During the initial stage of vortex formation, the crossflow detours the jet and forms the counter-rotating vortex on the lateral edges of jet.The subsequent vortex evolution depends very much upon the use of diffuser forms and the use of velocity ratios.The most complex vortex structure is found with the case of using slot diffuser.The latter has its major jet axis distributed along the streamwise.There are four separating points around the diffuser,and the separated flows gradually form four vortices.In the far zone, the jet flow is dominated by counter-rotating vortex pairs, which induce the formation of secondary vortex pairs in the near-wall region.The relation between the core position of counter-rotating vortex pairs and the velocity ratio for all types of diffuser forms is established, and so do for the rotating strength.