The existing design method for the channel width of immersed tube floating by tug towing has limitations.In response to this problem，a study is carried out on the floating channel width design based on numerical simulation.The floating channel width of the Shenzhen-Zhongshan Bridge gained from numerical simulation results grows with the time of tugs being in place，while decreases as the rectifying force increases.It is about 17 m smaller than the value calculated depending on the Design Code of General Layout for Sea Port.The design method of floating channel width based on numerical simulation takes into account the cooperative maneuver of tugs，enriches the width design method for immersed tube floating，and can provide a reference for similar projects.