The invention provides a design method of an LED (Light-Emitting Diode) driving circuit having a current-limiting protection function. The LED driving circuit comprises an LED array, a PWM (Pulse-Width Modulation) circuit, a constant-current diode and a photoelectric coupler. The design method has the advantages that 1, the driving circuit has the current-limiting protection function, so that an LED can be prevented from being damaged by large surge current caused by startup, lightening and the like, and the driving circuit is particularly suitable for driving an ultraviolet LED; the driving circuit is low in cost, and is small in size; 3, the output current of the PWM circuit becomes more stable through a feedback signal provided by the photoelectric coupler.