In order to obtain high-quality picosecond optical pulses, we proposed a three-stage pulse shaping scheme. A gain-switched semiconductor laser system was built to demonstrate the pulse shaping effect. The system is composed of temperature controlling and driving circuits, a semiconductor laser, a pulse compression element, and a pulse pedestal reduction element. Firstly, a dispersion compensated fiber (DCF) was used to compress optical pulse generated by a gain-switched semiconductor laser by reducing the pulse chirp. Then, the width of the optical pulse was further compressed by using the high-order soliton effect of an erbium-doped fiber amplifier (EDFA) and a dispersion shifted fiber (DSF). Finally, in the saturation operating state of a semiconductor optical amplifier (SOA), its self-phase modulation (SPM) effect was used to widen the spectrum, and an optical filter was used to filter the spectrum corresponding to the pulse pedestal, so as to reduce the pedestal of the optical pulse. The optical pulse width was compressed to 18.497ps. The experiment results show that this three-stage pulse shaping scheme can compress the pulse width and reduce the pulse pedestal effectively.