The invention relates to a direct-lighting backlight module which comprises a frame, a plurality of light-emitting diodes arranged at the bottom of the frame, as well as a first optical plate and a second optical plate sequentially arranged above the light-emitting diodes at intervals; the first optical plate and the second optical plate both are transparent bodies; the first optical plate comprises a plurality of parallel long-strip arc-shaped grooves which are formed at a light entry surface of the first optical plate and a plurality of parallel long-strip arc-shaped heaves which are formedat a light exit surface of the first optical plate; and the second optical plate comprises a plurality of parallel long-strip arc-shaped grooves which are formed at a light entry surface of the secondoptical plate and a plurality of parallel long-strip arc-shaped heaves which are formed at a light exit surface of the second optical plate and parallel to each other. The direct-lighting backlight module has better exit ray uniformity and is suitable for thinned design.