The water-soluble poly(o-phenylenediamine) was synthesized by chemically xxidative polymerization with ammonium persulfate as oxidant, sodium polystyrene sulfonate as template doping agent, o-phenylenediamine as monomer. The effect of dosage of oxidant to its electrical conductivity was discussed, its structure and electrochemical capability was tested by IR, UV and cyclic voltammogram, and a simple solid electrochromic device was assembled with PoPD/ PSS complex, it was found that the fastest of its response time was 1-2 and the lowest voltage was 0.9V which was likely to be used in environmental electrochromic devices.