The invention discloses a take-off warning system which comprises a flight warning computer, a red main warning lamp, an audio device, an engine operation system, a flight operation system, an undercarriage system, an avionics system and the like. The electrical input end of the flight warning computer is connected with all subsystems except for the red main warning lamp and the audio device in the take-off warning system. The electrical output end of the flight warning computer is connected with the red main warning lamp and the audio device. The flight warning computer comprehensively processes related information acquired through the input end according to a take-off warning logical judgment procedure and sends corresponding command information to the electrical output end to drive the main warning lamp and the audio device according to a processing result, and a sound warning and a lamplight warning are provided for a flight crew. By the adoption of the embodiment of the take-off warning system, the problem that a water surface take-off state warning is not available in takeoff warnings required by an airworthiness regulation can be solved, it is guaranteed that the take-off configuration warnings of an amphibious aircraft are completed, and the safety of an amphibious aircraft system is improved.