Jet flows often have an important role in the water environment. The aim of this research is to study the dilution of jets due to complex velocity fields induced by internal solitary waves in stratified water. Direct numerical simulations are used to study vertical jet flows during the propagation and breaking of internal solitary waves (ISWs) with elevation type on a slope. Energy analysis shows that the internal interface is able to absorb kinetic energy from the jet and that for Re < 10,000 with Ri > 3.7, the ISWs can stay stable during the propagation within the presence of jet flows. The vortices jointly induced by the jets and the ISWs are observed at the bottom behind the ISW’s crest. The transport of the jet’s emitted scalar by the ISWs can be divided into two parts; some is transported by the moving interface and the rest by the bottom vortices. The ultimate transport length scales of two types are defined, and it is found that when the center of the jet inlet approaches the slope, the extension of the bottom vortices into the slope will lead to strong mixing. That causes increasing scalar concentration over the slope of the scalar that originated from the jet.