Flip bucket is the main part of one energy dissipation structure called ski jump system. In this research, hydraulic characteristics such as jet length, velocity, pressure and Froude Number in four discharges are studied by Flow-3D in two models including spillway with simple flip bucket and spillway with approach channel. For turbulence modeling, RNG and k-e models are used. Validation show that k-e model is more accurate. The results indicate that the approach channel model has longer jet length and more energy dissipation compared to the other model. In this model, maximum velocity, equaling 2.30 meter per second, occurs at the beginning of the channel for 20 liters per second discharge. Also, maximum increase percentage in velocity happens in the model of approach channel spillway amounting 32 percent for discharge of 15 liters per second. The results of pressure analysis showed that the pressure changes in the two models have no tangible difference. Moreover, maximum pressure is on the toe of the spillway in the first model amounting 2833 Pa for discharge of 25 liters per second. Additionally, maximum Froude Number (4.5) occurs at jet fall in the simple flip bucket model and in approach channel model it occurs in the channel.