Novel microcellular foams using thin plasticized PC sheet were prepared by compression molding. The measurement results showed that Tg of plasticized PC was decreased and the molecular chain mobility was increased. Decrease in Tg and increase in chains mobility were contributed to the widen of foaming temperature window. Effects of processing conditions on cell size, cell density and relative density were also investigated. The experimental results show that the temperature, tributyl citrate and foaming agent content have more effects on the structures and morphology of the plasticized PC microcellular foam. Effects of experimental conditions on cell size distribution have also been discussed.