This article examines Sylvia Plath’s poems in terms of what Deleuze and Gattari call becoming-minority, focusing on her pursuit of new being and alternative order. First, her early poems show how solid identity is arranged within hierarchical arborescent system and how the system oppresses the human beings within it and destroys human life itself. But her poems also represent becoming-minority, specially becoming-animal and becoming-woman by forming the line of flight from molar being. Here becoming animal means that the speakers of poems become the molecular animal appropriating the speed and energy of mole, horse, lioness, and sting bee. This article also finds that her poems vividly reveal the process and success of transforming into molecular woman. “Fever 103” is the most important poem in the sense that it shows becoming-girl which means not regression but involution into a girl by forming the line of flight from the oppressive arborescent system based on the binary opposition between man and woman. Finally Plath succeeds in offering the alternative order of what Deleuze and Gattari call rhizome.