A foldable light source module and a backlight module with the light source module are provided. The light source module includes a first substrate, first light sources, a second substrate, and second light sources. The first substrate has a first surface and a first connecting portion. The first light sources are arranged in a line and disposed on the first surface. A first gap is kept between the neighboring first light sources. The second substrate which has a second surface and a second connecting portion is disposed parallel to the first substrate, wherein the second surface faces the first surface, and the second connecting portion connects to the first connecting portion. The second light sources are arranged in a line and disposed on the second surface. A second gap is kept between the neighboring second light sources. At least a portion of the second light source extends into the corresponding first gap and, conversely, at least a portion of the first light source extends into the corresponding second gap.