A backlight module and a backplate for use in the backlight module are disclosed. The backlight module comprises a light guide plate, a light source and a backplate; the backplate comprises a baseplate, side plates extending upwards from two opposite sides of the baseplate respectively, and top plates extending from the two side plates respectively and towards each other, and the side plates, the top plates and the baseplate together form recesses for receiving the light source, with two opposite edges of the light guide plate being disposed in the recesses; a fixing post is disposed at an end of the baseplate, and a fixing groove is formed in the light guide plate corresponding to the fixing post, with the fixing post being fitted in the fixing groove; and display panel positioning blocks are disposed at both ends of an upper surface of each of the top plates. Therefore, the backlight module of the present invention is compact in structure.