Water surface takeoff performance is the basic performance of surface aircraft, and it is also the core of the overall technology, involving multiple disciplines. The hydrodynamic performance of amphibious hydroplane at high speed taxiing on the still water surface is different from that of displacement boats, with high speed and complex movement characteristics, and it is subject to greater hydrodynamic and wing lift. Combines with the characteristics of high-speed taxiing on the surface of amphibious hydroplane, the numerical simulation of the whole aircraft model of amphibious aircraft was carried out by using RANS numerical method and overlapping grid technology. It analyses the characteristics of free liquid surface water vapor distribution and pressure distribution at the bottom of the fuselage, and compares the resistance, attitude and heave with the test results, which verifies the accuracy of the numerical method and provides a technical basis for the numerical prediction of hydrodynamic performance of hydrostatic taxiing of amphibious hydroplane.