In order to improve the performance of quantum dots fiber amplifiers, a strategy of compositing PbS quantum dots and mesoporous silica is proposed to increase the content of quantum dots on the tapered region of the fiber. The PbS quantum dots with oleic acid ligands loaded into the aminated mesoporous silica(NH2-MSN) through a single electron of nitrogen, and the quantum dots are enriched on NH2-MSN. NH2-MSN is connected to the hydroxylated optical fiber through hydrogen bond, so the density of PbS quantum dots on the tapered is greatly improved. The experimental results showed the on/off gain of the amplifier increased from 1.1 dB to 8.09 dB at 1550 nm with pump power increasing from 50 mW to 300 mW. The on/off gain finally saturated when the pump power is 280 mW.