The present disclosure provides a light source system and a lighting device including the same. The light source system includes at least one laser configured to emit excitation light, a substrate, a reflective layer, a wavelength conversion layer, and a light guiding element. The substrate is made of material with a high thermal conductivity and provided with a notch. The laser is received in a sidewall of the notch. The reflective layer covers walls of the notch and is configured to reflect the excitation light. The wavelength conversion layer is provided on a part of the reflective layer and configured to perform wavelength conversion on the excitation light to obtain excited light. The light guiding element covers an opening of the notch and configured to guide the excitation light and the excited light, to obtain light to be emitted by the light source system.