We proved the existence and uniqueness of comporessible subsonic impinging jet flow in the work \cite{WX}. As a continuation, in this paper, we investigate the shape of free boundary to the impinging jet flow established in \cite{WX}. More specifically, if the nozzle wall is concave to the fluid, then the free boundary of flow will be convex to the fluid. On another hand, the higher regularity of free boundary at separation point is obtained, provided that the nozzle satisfies corresponding hypotheses.