Abstract: Based on the 3-D numerical simulation and the model test,many factors affecting the flow pattern stability and the hydraulic characteristics of the horizontal Submerged Jets are studied. The results show that multi-lever and multi-strand horizontal submerged jets are a new energy dissipation type and have better stability of flow patter,lower velocity in the slab and higher dissipated energy rate than the single-lever and the multi-strand horizontal submerged jets. Connecting to the model test,some suggest ions,important for design,are put foward,for example,the chute width of intermediate outlet should be constant;the optimum height difference of drop between intermediate out let and surface outlet should be larger than the water depth at intermediate outlet;and the type of drop should be changed with the characteristics of certain project.