Tetrafluoroethylene(C2F4, TFE) was synthesized from the pyrolysis of difluorochloromethane(CHClF2, R22). The pyrolysis of R22 was investigated under the reaction conditions such as reaction temperature 400-800 ℃, residence time 0.07 sec and steam/R22 molar ratio 5. The Conversion of R22 increased with increase of temperature and the selectivity for TFE was showed maximum at about 650 ℃. To improve relatively poor yield of TFE at low temperature, Cu-based catalysts were introduced and their effects were studied. It was found that the conversion of R22 in the Cu-based catalytic pyrolysis was much higher than in the non-catalytic pyrolysis of R22 at temperature 650 ℃-750 ℃. However the presence of Cu-based catalysts resulted in decrease of the selectivity for TFE.