A laser projecting device and a light-combining lens are provided. The light-combining lens is a one-piece structure, and has a difference of refractive indexes less than 0.2. The light-combining lens includes collimation surfaces, reflection surfaces, and a light emergent surface. Each collimation surface defines a collimation path inside the light-combining lens. The reflection surfaces respectively located at the collimation paths are parallel to each other and arranged along an arrangement direction. The light emergent surface is located at the arrangement direction. Each reflection surface and the corresponding collimation path have an acute angle therebetween to define a reflection path. The reflection paths are overlapped in the light-combining lens to define a light-combining path. The light combining path passes through at least one of the reflection surfaces that allows light to pass therethrough along the light-combining path, and passes through the light-combining lens from the light emergent surface.