Abstract: The cyclic butylene terephthalate (CBT) was prepared by polycondensation reaction of 1, 4-butanediol and p-benzoyl chloride in ionic liquid at room temperature. The structure of the product was characterized by infrared spectrum and nuclear magnetic resonance. The cured CBT resin and fiberglass /CBT composite laminates were prepared by vacuum infusion process using dibutyltin dilaurate as catalyst. The forming process was studied and the mechanical properties of the samples were evaluated. The results showed that CBT resin with the desired chemical structure could be obtained by polycondensation polymerization when the molar ratio of p-benzoyl chloride to 1, 4-butanediol was 0.8 and the reaction time was 9 hours. When the catalyst dosage is 1.2ml/100g resin, molding temperature is 190℃ and fiber content is 70%, the cured resin and composite laminates with excellent mechanical properties can be obtained, which can meet the molding requirements of wind turbine blades.