A light source module includes a light source having an optical axis, a fan for providing a cooling airflow and a deflector disposed between the light source and the fan and directing a flowing direction of the cooling airflow. The deflector includes a first air duct connected between a first side of the light source and an air outlet of the fan, a second air duct connected between a second side of the light source and the air outlet of the fan, and a first airflow control assembly controlling the first air duct in a communicating state or a non-communicating state and having a first control shaft and a first airflow passing portion rotating about the first control shaft. The first control shaft is inclined to the optical axis so that a first angle is formed therebetween. The first angle is between 0 and 90 degrees.