The present disclosure provides a light guide plate assembly, a backlight source and a display device. The light guide plate assembly includes at least two light guide plates that are stacked on each other. Refractive indexes of the light guide plates are monotonously changed in a stacking direction of the light guide plates. One side of each light guide plate is provided with a refraction cavity. The refraction cavities of adjacent two light guide plates are disposed in two sides of the light guide plate assembly in a staggered manner. A light scattering layer is disposed at an inner wall that encloses the refraction cavity of each light guide plate.