Abstract: Synthesis and characterization of VTP/PS copolymer networks were presented. The effect of the unattached macromolecule chains on glass transition temperature T_g and dynamic mechanical properties in terms of storage modulus E', loss modulus E" and loss tangent tanδ of the copolymer networks were studied. The viscoelastic parameters were calculated. The results indicated that the unattached macromolecule chains can evidently plasticize the copolymer network,and there by decrease its T_g and increase the free fractional volume and tanδ of the copolymer.