A thin backlight module and a manufacturing method of the thin backlight module are provided. The thin backlight module includes a drive substrate, multiple light emitting sources, a fluorescence layer, and multiple particle micro-structures. The light emitting sources are arranged in an array on the drive substrate. The surface micro-structures are arranged on a surface of the fluorescence layer. Each surface micro-structure is arranged corresponding to each light emitting source. Each particle micro-structure is arranged corresponding to each surface micro-structure. Each particle micro-structure and each surface micro-structure together form a guiding layer for dispersing light from a corresponding one of the light emitting sources. Thereby, a smaller light mixing distance and an ultra-thin backlight module thickness are achieved.