In water conservancy projects, the outlet of the discharging structure is often built to face the channel river. In order to make the tail water flow smoothly to the river, a circular stilling well is always built to adapt to the terrain condition changes of mountains and canyons. Aiming at the complex hydraulic characteristics of the stilling wells where the tailwater outlet and the chute axis are asymmetrically orthogonal under certain longitudinal slope conditions, the finite field numerical simulation method was used to compare and verify the mechanical results of the short series experiment supplemented with the resuts of physical model test. Then the mechanism of related hydraulic elements along the direction of the space jet was analyzed. The research shows that the flow pattern of the water flow in the well experienced the evolution process of three critical Reynolds number partitions, namely from plane transverse turbulent diffusion free jet to mainstream dynamic self similar submerged jet to impinging jet and near wall adhesive diffusion whirling water jump. The change of the maximum flow velocity in the process was consistent with the calculation result of the semi empirical formula and showed an approximate plane diffusion distribution. The structural characteristics of the water body pressure can be decomposed into the superimposed distribution under horizontal axis symmetry and vertical amplitude.