Obesity is a complex metabolic disorder, which involves central mechanisms that control food intake and energy expenditure.The basic mechanisms that lead to obesity are not fully understood, however, oxytocin undoubtedly plays a role in regulating body weight. Previous studies have shown that central or peripheral oxytocin administration induces anorexia. But recently, some researchs have shown that rodents lack of oxytocin or its receptor develop late-onset obesity without changing their total food intake, which indicates the importance of oxytocin to energy metabolism. The effects of oxytocin on energy balance regulation is discussed in detail, especially the role of oxytocin on appetite regulation, thermoregulation, and energy metabolism.