Adolescence is considered as a time full of “storm and stress”. Numerous studies suggested that emotion regulation improves with age. While previous studies typically examined the developmental change of negative emotion regulation within a specific period, few studies considered regulation effect of both positive and negative emotions in a transitional period. To address this issue, one hundred and seven participants (35 young adolescents, range=13-15 years old; 37 old adolescents, range=16-18 years old; 35 young adults, range=20-29 years old) were examined for their up- and down-regulation of positive, neutral, and negative emotional stimuli. Results showed that: (a) considering the differences of emotion regulation effect among three age groups, a drop-down phenomenon was found in the old adolescents group. Specifically, old adolescents’ emotion regulation effect was the worst, while young adults’ was the best; (b) the effect of down-regulation improved more from early adolescence to early adulthood than the effect of up-regulation.