翁方綱是清代的重要詩論家，可是歷來研究者往往只圍繞他的「肌理說」來反覆討論。本文嘗試發掘翁方綱被人忽略的詩學理論，指出他曾主張「由蘇入杜」。翁方綱視「詩法」為總結歷代詩歌得來的創作原理、原則，認為杜甫是「詩法」的關鍵，將杜甫的「詩法」稱為「杜法」，詩人透過蘇軾詩可以正確地學得「杜法」。「杜法」之要，就在「精微」，但「精微」是心能領會，口不能言，所以要借助分析「肌理」顯現出來。翁方綱說「詩必研諸肌理」，就是這個意思，並不是說它最為重要。本文首先梳理「由蘇入杜」說的理論系統，然後分析其理論內涵，最後探討它在詩學史上的意義。

Although Weng Fanggang 翁方綱 was a prominent poetry critic, researchers have frequently only focused on discussing his jili shuo 肌理說 (theory of poetic texture). This paper intends to explore Weng’s relatively neglected poetry critiques and examine his advocacy of you Su ru Du 由蘇入杜 (approaching Du Fu 杜甫 through Su Shi 蘇軾). Weng sees shifa 詩法 (poetry writing skills) as the principles and theories summarized from shi (poems) written down the ages, stating that Du Fu’s poems are the key to shifa. He refers to Du Fu’s shifa as Dufa 杜法, and believes that one can come to a correct understanding of Dufa by studying Su Shi’s poems. The essence of Dufa is jingwei 精微 (refinement and detail), which can only be understood by the heart, and cannot be expressed in words. Thus, Weng argues, to help reveal it one must analyze the jili (texture) of a poem, but this does not mean that jili itself is of prime importance. This paper first catalogues you Su ru Du’s theoretical system, analyzes its content, and finally discusses its significance in the history of poetic theory.