In this work, the microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics based on sol-gel method prepared via different cooling methods (furnace cooling, air quenching, and water quenching) were systematically studied. The results showed that the dielectric constant of quick quenching samples (air quenching and water quenching) did not drop a lot contrasting to that of the furnace cooling CCTO ceramics. Furthermore, it was also found that the dielectric loss of air quenching CCTO ceramics decreased to 0.030, which was about 40% of the furnace cooling CCTO ceramics (0.074), and the dielectric loss of water quenching samples was as low as 0.044. In addition, the breakdown electric field could also be improved by air quenching. These enhancements could be attributed to the improved properties of the grain boundaries. The results above indicate that a proper quenching method can promote the dielectric properties of CCTO ceramics efficiently.