This paper is to analyze the differences between the 3rd edition and 4th edition of Oxford Advanced Learner's English- Chinese Dictionary (hereafter referred to as ALECD3 and ALECD4). By making comparison between the two dictionaries in the learner's and compiler's perspectives, it high-lights the priority of the 4th edition in content and compilation. Following a brief introduction in Part 1, Part 2 examines the innovations the 3rd edition has made in verb-pattern scheme, compounds, entries, examples, adjectives and appendices from the learner's perspective. Part3 holds a theoretical discussion of prescription and description in the 4th edition.
