Abstract: This article carries out a comparative study on the two prefaces of the retranslated Spanish version, published in 1988 and 2009, focusing on the differences of their hermeneutic contexts and horizons represented by the text. The research is intended to observe the conflicts, dialogue and fusion between the Chinese and western cultural horizons manifested in the adaptation of the preface of 2009 based on the one of 1988, so as to obtain a better understanding of attitude of the target culture towards the Chinese classic. It is found that the adapted preface retains the major part of the information and the social interpretive perspective of the original one, while paying more attention to Cao Xueqin’s personal trajectory of life, putting more emphasis on the theme of love and trying to highlight the mysteriousness of exotic atmosphere of the novel. The fusion of the adaptor’s horizon with that of the original preface is represented especially by the weakening of a political interpretation, the introduction of an individual interpretive perspective and the strengthening of reader awareness.