Abstract: Before utilizing computer technology, Multi-access keys remained as “card keys” for a long time. With the assistance of computer technology, however, many Multi-access keys retrieval systems have emerged. There are several typical Multi-access keys, such as DELTA, Lucid and NaviKey. This article compares the similarities and differences of the six mainstream Multi-access keys in architecture, user interface, database and retrieval strategies. For retrieval strategies, this article focuses on analyzing seven aspects: unrestricted character use, error tolerance, expressing uncertainty, numeric characters, best characters, retaining unknowns and diagnostic descriptions. In addition, computer-assisted Multi-access keys have diverse names at present, so we propose to use:“Multi-access keys” as its formal name.