Abstract: Conducting polymer based electrochromic materials can be applied widely in the area of smart window, anti-glaring rearview mirror, electronic tag and military camouflage, owing to their high contrast and fast switching speed. The electrochromic materials with superior performance can be obtained by molecular design of conducting polymer. In this paper, a water-soluble electrochromic material was prepared by copolymerization of aniline and m-phenylenediamine and using a macromolecular acid as dopant agent. The structure, electrochemical properties and electrochromic properties were characterized by Fourier Transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), Cyclic Voltammetry(CV) and Ultraviolet-visible (UV-vis) spectrometer. The results show that thanks to the branched molecular structure and loose aggregation structure of the copolymer, copolymer possesses higher structure stability, higher electrochemical activity and higher electrochromic properties than homopolymer.