As a non-coherent light source,the amplified spontaneous emission (ASE) sources play an important role in biomedical field. The pulsed ASE light source is used as a pumping source to stimulate the supercontinuum generated by the nonlinear medium, which has low temporal coherence and broad spectral characteristics, making it have a broader application prospects. The generation and amplification processes of a pulse ASE source are investigated . The nanosecond pulse ASE light source at a watt level is obtained. A fiber loop mirror structure is used to promote the in-band power, which resulting in a 280 mW continuous narrowband ASE output. And using an acousto-optic modulator and an electro-optic modulator to modulate a continuous narrowband ASE, with a pulse width of 8 ns, a repetition frequency of 50 kHz and an average power of 50 μW. The amplification process of ASE with different pulse shapes is studied in detail.