Abstarct:   Including important components of water conveyance networks are channel junctions. Due to the flow complexity in the channel junctions, empirical researches are time consuming and costly. Development of computer models and their capabilities, using those models has been considered. In this research, subcritical flow in 90 degrees four-branch junction using Flow-3D simulated and its capabilities has been evaluated. Results of calibration of numerical model showed that K-ω model with 560000 mesh and 5 mesh blocks produced the best results compared to experimental results. Comparison of the experimental and numerical results showed that Flow 3D has good performance in simulation of flow in channel junctions, so that RMSE and NRMSE errors were less than 10% and 15%, respectively. Numerical results approved that as increase of inlet discharge ratio, flow distribution and dimensions of separation zone in outlet channels increased and water surface fluctuations in junction increased. Change of height of weirs had no effect on flow distribution but water surface fluctuations and dimensions of separation zone decreased. Froude number has direct impact on the water surface fluctuation in junction and dimensions of separation zone in outlet channels. Also, investigation of velocity profiles showed that along the main channel at the junction entrance the velocity was more in the left wall and lower in the right wall, in the middle of the junction variations of velocity has linear trend. at the end of the junction, velocity was lower on the left wall and high on the right wall. Along the lateral channel, velocity variations at the entrance and end of junction had reverse trend. Along the inlet main and lateral channels, pressure distribution was constant and in the junction had nonlinear trend. Shear stress variations in the junction was similar to velocity results.