本文首先檢討過去學者對於《大乘莊嚴經論》三性說的討論，然後簡述單層結構與雙層結構兩種不同的三性說模型。據此對於現存《大乘莊嚴經論》的頌文進行仔細的文本分析，主張其中包含了單層與雙層結構兩種不同的三性說模型。現存《大乘莊嚴經論》頌文〈真實品〉中隱含支持的是單層結構三性說；但〈述求品〉明白主張的則是雙層結構三性說。類似的狀況也出現在《辯中邊論》中：〈相品〉與〈真實品〉分別主張單層與雙層結構的三性說。然而本文也進一步指出，不同於某些學者的主張，雙層結構三性說並不必然蘊涵依他起性是終極清淨的、因而無需滅除。事實上，本文認為在整部現存《大乘莊嚴經論》的頌文以及散文註釋中，都找不到明確支持「終極清淨依他起性」概念的證據。最後，依據現存《大乘莊嚴經論》中存在兩種三性說模型以及《攝大乘論》對於《大乘莊嚴經論》引用之不一致的兩個線索，本文建議現存《大乘莊嚴經論》頌文應該被視為是一個多層次的文獻，其中至少包含較古老以及較新的兩個文獻層次。

This paper begins with a criticial review of the scholarly discussions of the Theory of Three Natures (trisvabhāva-nirdeśa) in the Mahāyānasūtrâlaṃkāra. I then give a brief introduction to the two different models for the Theory of Three Natures, i.e., the single-layer vs. the double-layer model. With the distinction in mind, I carefully examine the verses in the Mahāyānasūtrâlaṃkāra and conclude that the sixth chapter implicitly supports the single-layer model whereas the eleventh chapter explicitly endorses the double-layer model. A similar situation, as I have argued, also appears in the Madhyântavibhāga (verses only): there the fi rst chapter supports the singled-layer model but the third chapter maintains the double-layer one. Different from other scholars’ opinions, I argue that even the double-layer model does not necessarily entail that the dependent nautre is ultimately pure and hence needs not be eliminated. In fact, I argue that throughout the whole Mahāyānasūtrâlaṃkāra (verses only) and the Mahāyānasūtrâlaṃkāra-bhāṣya the notion of “ultimately pure dependent nature” is nowhere found. Finally, based on the two clues— i.e., there are two different models for the Three of Three Natures and that the Mahāyānasaṃgraha is inconsistent when quoting from Mahāyānasūtrâlaṃkāra—, I suggest that our current version of the Mahāyānasūtrâlaṃkāra (verses only) should be viewed as a multilayered text, consisting of older and newer strata.