We investigated the possibility of using PET oligomers, which are made from PET waste by glycolysis, as the raw material for the synthesis of unsaturated polyester resin. The unsaturated and saturated polyester resins were synthesized from PET oligomer, propylene glycol, maleic anhydride and phthalic anhydride. The basic properties of these resins were analyzed and the curing characteristics were evaluated by DSC method. The reactivity of maleic anhydride to the glycols containing PET oligomer was higher than that of phthalic anhydride. Isothermal DSC method was properly applied to measure the curing reactivities of polyester resins, and the curing time of resin was decreased with increasing temperature. With the smaller ratio of glycol component to acid component in the reactants, we could prepare the unsaturated polyester resins of the higher molecular weight and the better curability.