Backlight module and combined light guide board structure used in same

The invention relates to a backlight module and a combined light guide board structure used in the same. The combined light guide board structure comprises a plurality of mutually spliced light guide boards, and each light guide board comprises a light incident surface, a light emergent surface adjoined to the light incident surface and a bottom surface opposite to the light emergent surface, wherein the bottom surface comprises a central part, a first inclined surface part and a second inclined surface part; the central parts are roughly parallel to the light emergent surfaces; the first inclined surface parts are adjoined to the central parts by inclining an angle relative to the light emergent surfaces; the second inclined surface parts are adjoined to the central parts by inclining an angle relative to the light emergent surfaces; and a light emitting unit is arranged on the light incident surface of each light guide board and emits out light towards the light incident surface to ensure that the light ent