Recently, many researchers have been interested in attachment processes in adolescence. However, the nature of attachment formation and transfer during this developmental period were not answered yet. This study examine the mechanism of attachment transfer from parents to friends, and the effects of childhood attachment styles on the level of attachment transfer and loneliness in adolescence. The resets show the majority of participants(70%) used their parents as primary attachment figures but were in the process of transferring attachment-related functions from parents to peers. There were the significant effects of attachment style, the level of transfer or state and trait loneliness in adolescence. This study provide the implications and limitation for conceptualization and measurement of adolescent attachment formation and loneliness.