Provided is a light source system, including: an excitation light source emitting excitation light; a wavelength conversion device having conversion and reflective regions located in different planes and time-sequentially located in optical path of the excitation light, the conversion region configured for converting at least part of the excitation light into excited light, and the reflective region configured for reflecting the excitation light; collection lens assembly configured to guide light from the conversion region to propagate along first direction to obtain first light, and guide the excitation light from the reflective region to propagate along second direction to obtain second light; first guide device configured to guide the excited light in the first light to exit along first path; and second guide device configured to guide the second light to propagate along second path. The first guide device combines the excited light and the second light to obtain source light.