Abstract: A fluorescence detection system is provided and adapted to provide a selectable excitation beam to an optical transmission path for irradiation of a device under test, including a driving module, a lighting module, a first optical module and a second optical module. The driving module includes a first shaft and a second shaft parallel thereto. The lighting module is fixed to the first shaft. The first optical module and the second optical module are fixed to the second shaft. A driving operation enables the driving module to rotate the lighting module, the first optical module and the second optical module simultaneously, determining quickly a combination of one light source, one filter and one spectroscopic module on the optical transmission path, with the combination corresponding in position to the device under test, so as to reduce the volume and cost the fluorescence detection system.