Disclosed is a driving device for driving a plurality of lighting fixtures, including a power converter for converting an input voltage into a DC output voltage; a plurality of lighting fixture bases connected in series with each other and each connected to a corresponding lighting fixture for outputting an operating voltage and an operating current to the lighting fixture. The operating voltage is derived by dividing the DC output voltage, and each operating current is identical with each other. The driving device further includes a plurality of output protection circuits respectively connected in parallel with a lighting fixture base for selectively bypass the lighting fixture base to stop the lighting fixture base from outputting current, and a control circuit connected to the output protection circuits for manipulating the output protection circuit to bypass the lighting fixture bases, thereby regulating the number of the lighting fixtures that illuminate.