A backlight module including a back plate and a heating device is disclosed. The back plate includes a passive layer and an active layer adhered below the passive layer, wherein a coefficient of heat expansion of the active layer is greater than that of the passive layer. The heating device is configured for controlling a heating temperature of the back plate so as to adjust a rate of curvature of the back plate toward a liquid crystal panel. In addition, a LCD and an OLED display device are also disclosed. The rates of curvature of the backlight module, the LCD, and the OLED display device may be adjusted accordingly.