Abstract: PDA has been applied to printed book acquisition and quasi-PDA acquisition modes have appeared in China. “You select books, and I pay” is a representative trend that grows in scale and takes a bigger proportion of funds. This paper analyzes the professional thinking of collection construction and compares PDA with quasi-PDA modes in terms of collection content and collection structure. It holds that quasi-PDA mode transfers library’s acquisition right to readers, and that, although it meets the personalized needs of readers to some extent, the quality of the purchased books is difficult to guarantee whereas hidden risks exist to collection system. Libraries should seek professional methods for the development of socialized management of literature, establish a professional quasi-PDA selection mechanism, balance the relationship of user demand and literature value, improve the expertise of librarians, and optimize quasi-PDA mode in a multi-mode and multi-level way, so as to improve the development of library collection.