A light source system includes an exciting light source, a collection system, a wavelength conversion device, a relay system, an optical-mechanical system, a detection device, and a distance adjustment device. The exciting light source emits exciting light. The conversion region converts the exciting light into excited light. Optical axes of the excited light and the exciting light that are emitted from the wavelength conversion device do not coincide with each other. The excited light and exciting light collected by the collection system are guided to the optical-mechanical system via the relay system. The detection device detects information on brightness and/or color coordinates of the light emitted from the optical-mechanical system. The distance adjustment device adjusts a distance between the collection system and the wavelength conversion device in such a manner that the brightness and/or color coordinates of the light emitted from the optical-mechanical system meet a preset condition.