A light source module adapted to provide a superposition structured pattern includes a light emitting device adapted to provide a light beam, a light guiding element including a polarizing beam splitter to separate the light beam into a first light beam and a second light beam, a first diffractive element configured to convert the first light beam into a first structured light, and a second diffractive element configured to convert the second light beam into a second structured light. Polarization states of the first light beam and the second light beam are different. The first and second structured lights are projected into a projection region, and overlapped and imaged as a superposition structured pattern. The projection region has sub-projection regions arranged in a matrix and adjacent to each other, and the pattern distribution of the superposition structured pattern in each sub-projection region is different from each other.