A light source structure of a backlight module includes a casing, a heat sink, a plurality of light source generators, a first reflecting element and a second reflecting element. If a light emitting component of the light source generator is lit, a spot light source of the light emitting component is passed through an optical lens in a light pipe and converted into a linear light source to be projected onto an oblique surface of the first reflecting element. The oblique surface converts the linear light source into a planar light source to be projected from an opening of a casing to an oblique surface of the second reflecting element. The oblique surface of the second reflecting element guides the planar light source into the light guide plate, such that the light in the light guide plate is diffused uniformly to provide sufficient brightness to the light guide plate.