Abstract: Modified by silane coupling agents,polyacrylonitrile(PAN) fiber was deposited with silver by electroless plating with solution containing rare earth lanthanum. The grain size of the silver particle,the crystal structure and surface morphology of the silver-coated fiber film,and the electrochemical property of the plating solution were characterized by nano particle sizer(Nano-ZS),X-ray diffraction(XRD),scanning electron microscopy(SEM),cathodic polarization curves,and cyclic voltammetry(CV),respectively. The effects of lanthanum nitrate on the speed of plating,quality of the silver film and electrochemical property of the plating solution were analyzed. The results showed that the speed of metallic ion depositing and the quality of the silver-coated fiber film were improved with the addition of appropriate amount of lanthanum nitrate in the plating solution. With the concentration of lanthanum nitrate increase from 0 g/L to 0.01 g/L in the plating solution,the polarization degree was increased,and the redox current peak and the speed of metallic ion deposition were also increased.