Lactonic crown ethers were synthesized by a novel insertion reaction of ethylene oxides into γ-butyrolactone (GBL) catalyzed by Al-Mg composite oxide, and the molecular structures of the target products were confirmed by FT-IR and ESI-MS. The process was optimized with respect to Al/Mg molar ratio of catalysts, reaction temperature and pressure. The conversion of GBL was 75.2% when the insertion reaction was catalyzed by 1 %(w/w) of LE-4 catalyst based on the target products and run in 5 times molar ratio of EO to GBL at160oC under 0.65 MPa.