The objective of the first part of the article is to settle, through the exemplary 1 1Q5 's case, the divergences there are between the psalmical manuscripts from Qumran and the biblical Psalm-book. Then, a brief point regarding this question is done with a critical view witch is giving some new approaching ways to the study of the so-called "Psalm-book's" manuscripts and also to the research dealing with the relationship between the Psalm-text of the judean desert and the biblical Psalm-book. The second part of the article grapples with the different ways of quoting the Psalm-book inside Qumran's manuscripts : on the one hand through the Hodayot (adulatory praises), on the second hand with the exegetical works alike the thematical pesharim and midrashim.</jats:p