In the existing bridge expansion device. The modular expansion device is widely used in bridge engineering because of its durable structure, good waterproof performance and convenient installation. However, the height of the existing modular expansion device is relatively high, and deep installation notches should be reserved at the end of the beam body before installation. Shallow buried modular expansion device is a new type of practical expansion device designed for the shallow reserved installation slot of the beam body, and the conventional modular expansion device can not be installed.