A light source module comprises a case, a light source, a first air-circulation device, a second air-circulation device and an airflow guide. The case has an airflow outlet, and other components are disposed therein. The airflow guider includes a first stream-guiding part and a second stream-guiding part connected thereto. The first stream-guiding part and the airflow outlet are at a same side of the light source, the second stream-guiding part is over the light source. The first airflow provided by the first air-circulation device passes past the light source, arrives at the first stream-guiding part, flows from the front of the light source towards the back of the light source guided by the second stream-guiding part, and mixes up with the second airflow provided by the second air-circulation device and finally exits from the airflow outlet. Therefore, concentrated heat is prevented at the airflow outlet.