Abstract: The conditions and influence factors of de novo synthesis of polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) in municipal waste incinerators were analyzed . The influence of CuCl2，carbon content，partial pressure of oxygen，reaction temperature and time on the de novo synthesis of PCDD/F were studied. The results indicated that CuCl2 was the most obvious and effective activator. The de dovo synthesis of PCDD/F was favored within a temperature range from 250℃ to 450℃ and a maximum value was reached at 300℃. Measurements and methods were proposed to reduce the PCDD/F formation. A new typical medical waste pyrolysis equipment (3t/d) was designed and developed，and the pyrolysis gas and solid residue were tested .The results showed that most of the HCl，SO2 generated during the pyrolysis process was fixed in the residue，and there was little HCl and SO2 left in the pyrolysis gas，which was much lower than the Chinese standard for emission.