In this work, a series of antibacterial poly(ether-amide)/silver nanocomposites (PANCs) was prepared via in situ preparation of Ag nanoparticles within a new poly(ether-amide) (PA) matrix. A new type of dicarboxylic acid (DA) containing ether and aliphatic moieties was successfully synthesized via a solvent-free reaction. Then a new PA with high solubility in common organic solvents was synthesized from a direct reaction of 4,4-diamino diphenylmethane and the DA. Silver nanoparticles were embedded within the PA chains through using a silver/ammonia complex [Ag(NH3)2]+. The formation of nano silver was confirmed by X-ray diffraction, transmission electron microscopy, and UV–vis spectroscopy. The effect of Ag nanoparticles on thermal properties of the prepared nanocomposites was studied by the thermogravimetric analysis. The results showed that the thermal properties of the nanocomposites were improved as compared with the neat PA. The antibacterial capability of the PANCs was studied by the disk diffusion method against Escherichia coli, which suggested that the PANCs can be considered as good antibacterial agents.