The present invention provides a backlight module and a liquid crystal display apparatus. A light guide plate of the backlight module comprises hollow structures. Each of the hollow structures corresponds to one of the light sources and comprises two air layers with an included angle there-between, and the two air layers are a first hollow layer and a second hollow layer. A normal direction is vertical to the light-incident surface, and there is a first oblique angle between the first hollow layer and the normal direction, and there is a second oblique angle between the second hollow layer and the normal direction, and a depth of the hollow structures satisfies a predetermined equation.