The good properties of non-crystalline state,high thermal stability,and high energy have made polynitropolyphenylene(PNP) a promising energetic polymer in the field of explosives and propellants. PNP was synthesized via polymerization using dichlorotrinitrobenzene as starting material. The important parameters affecting the polymerization were analyzed and dicussed in this paper. The obtained relative molecular mass of PNP,thermal decompostion temperature,and bulk density were all determined.