The invention relates to a sea-air amphibious aircraft with fixed wings and gliders, which comprises a flight control device assembly, an underwater control device assembly and a waterproof sealed cabin assembly. The flight device assembly is connected with a waterproof enclosure assembly, and comprises a rotor assembly, a main wing assembly and a tail wing assembly, wherein the tail wing assemblycomprises a fixed tail wing, a vertical wing and a horizontal wing; the underwater control unit assembly is located within the waterproof enclosure assembly and includes the forward most water bag and pumping and drainage control system assembly. The aircarft combines the design concept of the fixed-wing aircraft and the underwater glider, adopts the structure of the fixed-wing aircraft and combines the motion control system of the underwater glider, and can realize the long-distance, high-speed and high-efficiency flight in the air, and also can realize the long-time, long-distance and low-power consumption underwater gliding navigation. The gliding path can be set freely according to the demand, and the sawtooth-like or spiral floating motion can be carried out efficiently. It has a wide range of applications, such as fast large-scale water sampling, sea-air joint observation and so on.