Ectotherms rely primarily on behavioral thermoregulation to raise their body temperatures. Traditionally, it is assumed that behavioral thermoregulation only exists in post-embryonic stages. However, recent studies have shown that reptile embryos have the capability of behavioral thermoregulation. Here we review the discovery and research progress of behavioral thermoregulation in reptile embryos, discuss the ecological and adaptive significance of behavioral thermoregulation in embryos, analyze how embryos sense temperature to complete behavioral thermoregulation, and point out some future research directions in this field.