The invention relates to the technical field of automobile passive safety and provides a flat tire protection device. The flat tire protection device comprises a gas generation unit, a flat tire linkage unit and an air bag assembly filled with gas to be used for supporting a tire when the tire bursts. The flat tire linkage unit comprises a first cylinder body with an opening formed in one end and a first action piece arranged in the first cylinder body. The first cylinder body is divided by the first action piece into a closed first cavity and a second cavity used for communicating with an inner cavity of the tire. The gas generation unit communicates with the air bag assembly and used for generating gas when the tire bursts and making the air bag assembly filled. The gas generation unit is electrically connected with the flat tire linkage unit. The first action piece is used for controlling a circuit where the gas generation unit and the flat tire linkage unit are located to be on and off. The flat tire protection device is arranged in the inner cavity of the tire, the structure of the tire is not changed at all, and the elasticity of the tire, noise generated in the traveling process, oil consumption, the controllability and the like cannot be adversely affected.