To synthesize new main-chain aliphatic carbonate liquid crystal (LC) copolymers Dios-(CH2)(6)-(TMC)(x)-(DLLA)(y), a compound of diosgenyl derivative Dios-(CH2)(6)-OH was used as an initiator and reactant through the ring-opening polymerization of 1,3-trimethylene carbonate and d,l-lactide without other catalyst. The chemical structures of the copolymers obtained in this study were characterized by Fourier transform infrared spectrum and proton nuclear magnetic resonance spectrum. Their LC properties were investigated by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction measurement. The effect of the diosgenyl derivative content on mesophase and phase transition temperature of the copolymers was discussed. It was found that three copolymers all displayed fan-shaped texture of a smectic A phase. The results seemed to show an increased tendency toward the isotropic temperature for the LC copolymers with increasing the content of the diosgenyl derivative.