The floating transportation and installation of the immersed tunnel segment, as the key of Hong KongZhuhaiMacao Bridge, is a continuous constraction process. In this paper,a management system of the operation window is proposed based on the capacity of towboat and equipment to reduce the operation risk; and the operation limits are put forward to find the best operation time. The tide is the key factor for operation window, based on which a 24-36 hours of floating transportation and installation plan for immersed tunnel segment is compiled; the plan is carried out strictly under the best hydrological and meteorological conditions. The successful floating transportation and installation of 33 immersed tunnel segments show that the operation window management system can meet relevant requirements, guarantee the safety of floating transportation and installation of the immersed tunnel segment and reduce the operation risk and cost.