Connecting an input port and an output port of a single-mode fiber coupler to form a fiber-loop, and making the time delay of the fiber-loop odd times the half-period of the input optical pulses, optical pulses with a multiplying repetition rate at the other output port of the coupler were obtained. Utilizing three loop-connecting fiber couplers concatenated, optical pulses with an eight-times repetition rate were obtained. Experimental results show that, this scheme has several advantages, such as easy adjusting for pulse amplitude and pulse interval, large output power, low cost and easy fabrication.