A backlight module includes a light box and multiple real light sources. The light box has an opening and a plurality of substantially parallel grooves recessed from a bottom surface thereof. Each of the slots has a reflection curved surface. A light source allocation line is defined between every two adjacent grooves. The light source allocation lines are parallel to the grooves. The sum of shortest distances between any point of the reflection curved surface and the two adjacent light source allocation lines is substantially the same. In addition, the real light sources are alternately allocated in the light source allocation lines. A part of light emitted from each light source is reflected from the reflection curved surface to the light source allocation line in which no light source is allocated. Thereby, a virtual light source is formed on the light source allocation line that does not contain a real light source.