Provided are a main board fixing device, a display module, and a display device (400). The main board fixing device comprises a PCB main board (1), a first elastomer (5) and a second elastomer (3). The first elastomer (5) and the second elastomer (3) are respectively provided at a first side and a second side of the PCB main board (1), wherein the first side and the second side are symmetrical. The display module comprises the main board fixing device. The display device (400) comprises the display module. The main board fixing device enables the PCB main board (1) of the display module to be detached easily.