A light source module, comprising: a substrate; a light emitting device, disposed on a surface of the substrate and configured to emit a light beam; a package structure (120, 120A, 120B), disposed on the surface of the substrate and covering the light emitting device, wherein the package structure (120, 120A, 120B) has a first groove (120g1) and a second groove (120g2, 120g2A, 120g2B) connected to each other, the package structure (120, 120A, 120B) is transparent to the light beam, the light emitting device is located between the first groove (120g1) and the substrate, the second groove (120g2, 120g2A, 120g2B) is located between the first groove (120g1) and the substrate, an orthogonal projection of a region occupied by the first groove (120g1) on the substrate has a geometric center, the light emitting device is located at the geometric center, and an orthogonal projection of a region occupied by the second groove (120g2, 120g2A, 120g2B) on the substrate is not overlapped with the geometric center; and an optical pattern (130, 130A), disposed in the first groove (120g1) and the second groove (120g2, 120g2A, 120g2B) and being transflective, the light source module being characterized in that the package structure further comprises a third groove (120g3) defined by a ridge, wherein the ridge surrounds the first groove and the second groove, the orthogonal projections of the regions occupied by the first groove (120g1) and the second groove (120g2, 120g2A, 120g2B) on the surface of the substrate are completely overlapped with the orthogonal projection of the region occupied by the third groove (120g3) on the surface of the substrate, and that the package structure (120, 120A, 120B) surrounds the optical pattern (130, 130A). a substrate; a light emitting device, disposed on a surface of the substrate and configured to emit a light beam; a package structure (120, 120A, 120B), disposed on the surface of the substrate and covering the light emitting device, wherein the package structure (120, 120A, 120B) has a first groove (120g1) and a second groove (120g2, 120g2A, 120g2B) connected to each other, the package structure (120, 120A, 120B) is transparent to the light beam, the light emitting device is located between the first groove (120g1) and the substrate, the second groove (120g2, 120g2A, 120g2B) is located between the first groove (120g1) and the substrate, an orthogonal projection of a region occupied by the first groove (120g1) on the substrate has a geometric center, the light emitting device is located at the geometric center, and an orthogonal projection of a region occupied by the second groove (120g2, 120g2A, 120g2B) on the substrate is not overlapped with the geometric center; and an optical pattern (130, 130A), disposed in the first groove (120g1) and the second groove (120g2, 120g2A, 120g2B) and being transflective, the light source module being characterized in that the package structure further comprises a third groove (120g3) defined by a ridge, wherein the ridge surrounds the first groove and the second groove, the orthogonal projections of the regions occupied by the first groove (120g1) and the second groove (120g2, 120g2A, 120g2B) on the surface of the substrate are completely overlapped with the orthogonal projection of the region occupied by the third groove (120g3) on the surface of the substrate, and that the package structure (120, 120A, 120B) surrounds the optical pattern (130, 130A). the package structure further comprises a third groove (120g3) defined by a ridge, wherein the ridge surrounds the first groove and the second groove, the orthogonal projections of the regions occupied by the first groove (120g1) and the second groove (120g2, 120g2A, 120g2B) on the surface of the substrate are completely overlapped with the orthogonal projection of the region occupied by the third groove (120g3) on the surface of the substrate, and that the package structure (120, 120A, 120B) surrounds the optical pattern (130, 130A).