The brain mechanisms of fear and its regulation in adolescents from 10 to 17 years old were investigated by using fMRI (functional Magnetic Resonance Imaging) and EEG (electroencephalogram) techniques. In the fMRI study, thirty right-handed healthy adolescents (from 10 to 17 years old) viewed blocks of fearful faces (10 faces) alternating with neutral faces in blocks (10 faces). After presentation of each face, subjects made a decision as to its sex by pressing one of two buttons. Then subjects viewed blocks of fearful pictures (10 pictures) alternating with neutral faces in blocks (10 pictures). Each experiment comprised eight separate 30-s presentation phases, alternating between 10 fearful and 10 neutral stimuli. In EEG study, emotional EEG was recorded from forty-six right-handed healthy adolescents (from 12 to 16 years old). The EEG study included "Attend trials" and "Reappraise trials". On Attend trials, either a fearful or a neutral picture was shown and participants were instructed to attend to, but not to try to alter any feelings elicited by it. On Reappraise trials, a fearful picture was shown and participants were instructed to reinterpret the picture so that no longer elicited a negative response. Results and conclusions: Adolescents (from 10 to 17 years old) reported higher affective experience in the response to fearful pictures and fearful faces with grade. Significant activation was observed in the limbic lobe, right amygdala and occipital lobe during the facial expressions task and the picture task. Significant activation was also observed in the temporal lobe, left amygdala and right frontal lobe during the picture task. The activation in the left frontal lobe and occipital lobe was greater with age during the task. Significant activation was observed in the amygdala in adolescents from 10 to 15 years old during the task. No significant activation was observed in the amygdala in adolescents from 15 to 17 years old during the task. There was greater activation in the limbic lobe, frontal lobe and occipital lobe in girls than in boys during the picture task. Adolescents (12-14 years old ) displayed larger 11.72-Hz a 2-band at the left prefrontal lobe and smaller 9.77-Hz a 1-band at the right parietal lobe when they were instructed to Attend fear picture than to Attend neutral pictures. In contrast, adolescents (15-16 years) displayed larger 11.72-Hza 2-band at the frontal lobe and larger 10.74-Hz a 1-band at the rightfrontal lobe and larger 8.79-Hz a 1-band at the frontal lobe and smaller 9.77-Hz a 1-band at the central frontal lobe and the left hemisphere and the parietal lobe when they were instructed to Attend fear picture than to Attend fearful picture. The development of the prefrontal lobe is the brain mechanisms of the development of fear in adolescents. The brain is plastic in adolescent stage. These results were consistent with Davidson et al.'s findings.EEG was used firstly to examine the brain mechanisms underlying emotion regulation. The EEG study showed that 9 -band amplitude at the frontal lobe and the left temporal lobe was related to emotion regulation of fear in adolescents. Adolescents (12-14 years old) displayed smaller 6.84-Hz theta-band at the left frontal lobe and the left temporal lobe and smaller 5.86-Hz theta-band at the central frontal lobe and the right frontal lobe when they were instructed to regulate fear than to watch fearful pictures. In contrast, adolescents (15-16 years) displayed smaller 4.88-Hz theta-band at the frontal lobe and the left temporal lobe and smaller 5.86-Hz theta-band at the frontal lobe and the right parietal lobe at when they were instructed to regulate fear than to watch fearful pictures. In this study, new model was developed to explore the brain mechanisms underlying emotion regulation. EEG can be used to examine emotion regulation. The proposals from the neuropsychological theories for emotion were demenstrated. The prefrontal lobe is the brain mechanisms underlying the development of fear and its regulation. This study had theoretical and