Influence of the interaction between the streamwise vortices produced by a ramp in a supersonic flow and twin swirling jets for the mixing enhancement was experimentally investigated. Nominal Mach number of the main air stream and the twin swirl jets were 2.35 and 2.0, respectively. The directions of swirls were opposite and same with the streamwise vortices produced by the ramp. Three dimensional velocity distributions were measured using a Particle Image Velocimetry (PIV). Mie scattering images of the particles seeded in the injectant on cross section of the duct were recorded. In the opposite swirl case, strong outward flow was observed at the interaction point of the swirl in the jet and the ramp vortex. Mie-scattering images showed the difference of the injectant trajectories with the swirling condition. In the opposite swirl case, the injectant spread more widely and the injectant attached on the wall most slowly in the three cases.