Deep Brain Stimulation (DBS) is a surgical medical treatment involving the implantation of a medical artificial device which sends electrical impulses to specific parts of the brain. DBS in the selected brain areas has provided remarkable therapeutic benefits for treatment-resistant diseases, such as Parkinson's disease. DBS can directly change brain activities in a controlled manner, and its effects are reversible. Lately, the clinical trials of DBS have been applied to various psychiatric disorders in EU, USA and Canada, such as obsessive compulsive disorder, Tourette syndrome and severe depression. Nevertheless, DBS therapies for affective disorders are still at the experimental stage and they may contain risks in implanting the device into a person's brain which possibly alters that person's brain function and hence his personal identity. Based on the experiences of Germany and France, this paper will examine the safety of DBS treatment for psychiatric disorders, the patient selection criteria, and etc.. The conditions for proper application of the DBS technique will also be clarified hereby. It will be argued in this paper that for psychiatric diseases, the DBS specialists can never decide alone and psychiatrists always need to be consulted to avoid possible failures resulting from mistakes in applying this technique. In real practice, the medical doctors usually consider that very sick adult patients are competent to give informed consent. Although the formal signature of consent from a family member is not a compulsory requirement family support for patients is considered crucially important. In France, the consent of the patient is the principal requirement for adopting DBS treatment; yet, the situation becomes difficult when the patient is considered unable to make an informed and rational decision. Under such circumstances, the decision could be then made by a legal representative. Previous medical practices of lobotomy have revealed many problems and concerns which need to be resolved. Although lobotomy has certain benefits, it has been over applied to massive cases without any well-defined criteria and its practice was also poorly designed. Therefore, the new techniques of DBS must be considerably better defined in terms of its criteria, procedure and ethical boundaries to avoid possible bioethical mistakes.