The mechanical properties of the novel plasticized microcellular PC thin sheets using tributyl citrate as plasticizer and prepared by compression molding have been investigated. The tensile testes showed that the foaming temperature and the TBC content had pronounced effects on the tensile modulus and strength, the stress-strain curves of foamed plasticized PC were very different from that of unfoamed PC and the characterizations of the stress-strain curves of foamed plasticized PC strongly depended on the relative density. Besides, the relative tensile modulus and strength were also investigated as functions of the relative density and several empirical functions have been established.