This paper studies the poetic forms of Sidney’s Sonnet 108 by focusing on its sharply contrasting structural pattern. The paper applies some concepts of New Criticism that emphasizes the organic unity of form and meaning in literary works， especially in poetry. The organic unity of form and meaning of Sonnet 108 is accomplished by using “complex tropes and images such as metaphor， symbol， irony， and paradox” (Ryan 5). The whole sonnet is based on the pattern of sharp contrasts， and the sharp contrasting pattern develops in two ways: the horizontal way and the vertical way. The horizontal way is formed with parallel polarizing antonyms， antitheses and contrasting images， while the vertical way is structured with an axis of both up-down and down-up images. In either way， the sharp contrasting pattern skillfully leads to the important final paradox， fully shown in the concluding couplet. This final paradox that is artistically developed in the first three quatrains and clearly shown in the final couplet demonstrates the logically convincing result in form. It is also a brilliant example to show the organic unity of form and meaning of the poem because the whole sonnet expresses Astrophil’s conflicting emotions of sorrow and joy of love which will never materialize， nor will it die in his deep heart; thus it will surface and resurface without a definite conclusion， and so it forever leaves Astrophil’s love to a vulnerable open situation without any seeable and possible accomplishment. So Sidney’s sonnet sequence ends with Sonnet 108， but the movement of his sorrow-love and love-sorrow will definitely continue without an end.