A light source assembly includes a plurality of light source modules. Each of the light source modules includes a base, a light emitting unit and a light guide member. The light guide member has an accommodating space. The light emitting unit and the light guide member are disposed on the base and the light emitting unit is located in the accommodating space. At least one of the base and the light guide member has a first connecting structure and a second connecting structure. The first connecting structure of one of the light source modules is connected to the second connecting structure of another one of the light source modules, such that the light source modules are connected to each other to form the light source assembly.