A light source module includes a substrate, a light emitting device, a package structure, and an optical pattern. The light emitting device and the package structure are disposed on a surface of the substrate, and the package structure covers the light emitting device. The package structure has a first groove and a second groove connected to each other. The light emitting device is located between the first grove and the substrate. The second groove is located between the first groove and the substrate. An orthogonal projection of the region occupied by the first groove on the substrate has a geometric center. The light emitting device is located at the geometric center. An orthogonal projection of the region occupied by the second groove on the substrate does not overlap the geometric center. The optical pattern is disposed in the first groove and the second groove, and is transflective.