The disclosure discloses a light source module of a luminaire including a light source board, a heat dissipating component, a first sleeving component, and a second sleeving component, wherein the heat dissipating component includes a mounting base portion; the second sleeving component is sleeved on the first sleeving component and presses the light source board on the mounting base portion; the light source board includes illuminators; the first sleeving component has an avoidance space, and the illuminators are located in the avoidance space; and at least a region, opposing to the illuminators, of the second sleeving component is a light transmission region.