Disclosed are a light source system (10) and a projection device. The light source system (10) includes: a first light source (11) emitting first laser; a wavelength conversion device (13) including three primary color light regions and one mixed color light region; a driver device (19) driving the wavelength conversion device (13) to move in such a manner that regions of the wavelength conversion device (13) sequentially and periodically receive the first laser; a second light source (12) emitting supplementary light consistent in color with light emitted by one primary color light region; a control device (18) controlling on and off of the second light source (12), the control device (18) controlling the second light source (12) to be on in at least two of: every time period during which a primary color light region of a same color is receiving the first laser, every time period during which the mixed color light region is receiving the first laser, and some time periods during which a primary color light region of a different color is receiving the first laser. In this way, the light source system (10) of a high luminous flux and high supplementary light source utilization rate is obtained.