High molecular weight poly( phenylene sulfide sulfone/phenylene sulfide ketone) copolymer was synthesized by the step polycondensation of sodium sulfide (Na2S center dot xH(2)O) with 4,4'-dichlorobenosulfone (DCDPS), 4,4'-difldibenzophenone ( DFBP) between 180 similar to 202 degrees C at normal pressure. The copolymer was characterized by FT-IR spectrum, UV spectrum, H-1-NMR spectrum, X-ray diffraction and small angle light scattering (SALS), DSC and TGA. The more ketone in the copolymer chain, the better thermal properties of the PPSS/Ks resins have. The copolymer was found to be amorphous but has little local ordering structures with the content of ketone in the range of 0 similar to 45% which is different from other high pressure polymerization.