Rectangular dissipation wells with oblique inlets are well suited to narrow terrains of remote mountainous areas; however, the dissipation effect of the wells is directly affected by the turbulence and energy dissipation of the oblique jet. Here, the large eddy simulation method is used to study the turbulence characteristics of the jet in a rectangular dissipation well under a specific flow rate. The results show that the axis area of the primary submerged flow at the jet direction displays an irrotational motion, whereas rotating vortices of varying sizes and strengths are concentrated around the water stream (absolute reduction rate of relative vortices along the jet falls in the range of 74%-92%). The vortex intensity is greater in the front part of the jet, where the vortex structure is visibly disrupted and the distribution thickness is small. In the middle section of the jet, the range of vortex separation and fusion gradually expands, the adjacent vortex areas begin to form strip structures, and the vortex intensity decreases significantly. In the rear section of the jet, the turbulent vortex is further disrupted, twisted, and spreads outwards, resulting in a further decrease in vortex intensity. The distribution of turbulence intensity around the jet exhibits a clear pattern, with low intensity in the center and high intensity around the jet. This distribution also demonstrates a certain self-similarity. Specifically, the turbulence intensity gradually increases along the path of the jet water stream in the front and middle sections (an increase of 12%-14%). In the rear section, the turbulence intensity tends to be more uniform around the jet, but gradually decreases as it progresses (a decrease of about 28%). The turbulence dissipation of the jet is primarily concentrated in the shear layer region at the periphery of the jet (kinetic energy attenuation rate ranges from 83% to 91%). In the front section of the jet, the turbulence dissipation is not prominent, and it still carries a significant amount of kinetic energy. As the jet progresses, the turbulence dissipation rate increases in the middle section, but gradually decreases in the rear section. It is evident that the primary cause of the dissipation of jet turbulence is the energy exchange between the jet vortex and the surrounding water body. The energy dissipation primarily takes place in the mid-region prior to the jet deflection, and the kinetic energy attenuation of the jet is greater than 60%.