The utility model relates to a module expansion device suitable for bridges in roads and city highways. The expansion device is characterized in that compression control springs of a displacement control system are installed in a positive-negative direction coupled mode, a displacement box is arranged, the compression control spring is arranged between supporting hangers, a reversed-installed compression control spring, a positive-installed compression control spring and a reversed-installed compression control spring are sequentially arranged on a gap between a boundary beam steel and a middle beam along a cross beam from left to right, or a positive-installed compression control spring, a reversed-installed compression control spring and a positive-installed compression control spring are sequentially arranged on a gap between a boundary beam steel and a middle beam along a cross beam from left to right. If a reversed-installed compression control spring is arranged in the front of two sides of the cross beam, a positive-installed compression control spring at the back of two sides of the cross beam. The module expansion device is compact in design, can operate well and has even gap between the middle beam steel and the boundary beam steel since the springs are arranged in a positive-negative direction coupled mode, and accordingly, uneven expansion between beams of large displacement expansion device in home and abroad is avoided.