A simulated sunlight generating device for generating a simulated sunlight required for evaluating performance of solar cells includes a plurality of driving units, a plurality of light-emitting units, and a plurality of adjusting units. The driving units drive the light-emitting units to emit light. The adjusting units enable the light of the light-emitting units to not only propagate along the same light route but also be added up and combined to form the simulated sunlight of an intended wavelength with ease of installation, ease of maintenance, low costs, high flexibility, and high efficiency.