A PbS quantum-dot-doped fiber amplifier (QDFA) is realized experimentally in NIR S-C-L ultra-broad waveband and with low noise. Taking UV-gel as the optical fiber background and PbS quantum dots (QDs) as the gain medium in the fiber, we setup a full-light path structure composed of a 973 nm pumping single mode laser, an isolator, a wavelength division multiplexing and a quantum-dot-doped fiber. The broadband signal light with the range of 1470-1620 nm is amplified in an all-optical structure. There is evidence to show that the QDFA has 75 nm bandwidth around the wavelength region of 1550 nm with the switch gain of 16 dB-19 dB (the net gain of 12.26 dB-15.26 dB) for the input signal power of -23 dBm and the noise figure of about 3 dB. An obvious excitation threshold and gain saturation phenomenon are observed by the experiment. A linear relationship is determined between QD doping concentrations and fiber length. The obtained performances in the bandwidth, C-waveband gain flatness and noise figure of QDFA in this paper are better than those of the conventional erbium-doped fiber amplifiers (EDFAs), while the L-waveband gain flatness is a little lower than that of the optimized EDFAs.