Abstract: The present invention provides a light source assembly applied to an alarm device, which comprises a base; a light source arranged on the base and configured to emit visible light; and a lens arranged on an emission path of the light source and configured to modulate the visible light emitted by the light source into a light distribution curve conforming to the presetting. According to the light source assembly and the alarm device including the same in the embodiment of the present invention, the light emitted by the light source is modulated through the lens, so that the angle of emission of the light source assembly and the alarm device can be fully expanded. Especially when the light source assembly and the alarm device are applied to fire-fighting devices, the alarm reception blind area can be effectively reduced, and the safety level is improved.