Annotation allows users to take and share notes without face-to-face interaction and supports them to acquire the mobility of notes, and the flexibility of time and place for reading and learning. The paper firstly introduces the web learning environment and analyzes the existing software with annotating function. In the annotation system, annotation tools are added to Explorer Bar of IE Browser, which could annotate webpage in every server. On the Webpage which annotated, annotation could insert to the Web documents in the designated position, which is added to HTML documents of the Webpage actually, but will not revise the HTML documents itself. It includes four modules: add-annotation tool, search-annotation tool, annotation service platform, installation and uninstall tools of system. By the analysis of the system architecture and division of the function modules, we develop the annotating system, which includes 2 parts: adding annotation and searching annotation based on IE.