Internet addiction (IA) as a behavioral addiction is currently becoming a serious mental health issue around the globe. According to the neurobiological model of brain development, exploring the neural mechanisms of reward seeking behavior and cognitive control in internet addicts may help in developing treatments for individuals with IA. Behavioral research has indicated that IA is commonly associated with enhanced reward sensitivity and decreased inhibitory control. Additionally, research focused on the neural mechanisms of IA indicates that deficits in the reward or cognitive control systems might be a high risk factor for addictive behaviors. Compared with substance addictions, IA, as a kind of psychological addiction, has a specific reward mechanism. While previous research has deepened the understanding of the psychological and neural mechanisms in IA, there still exist many issues surrounding diagnosis and treatment of IA: the screening criteria are not scientific; the classification is ambiguous; the effect of intervention and treatment is controversial; causal research is scarce; and research paradigms are flawed. Substantial future research is needed to explore, fully understand, and treat IA.