Filling in online forms has become a daily behavior. However, when users fill in online forms, they often confront difficulties. It is necessary to consider how to improve the online form design. The study took web resume as an example; four resume prototypes were created for user testing, and researchers conducted contextual inquiry and interviews related to these. The results revealed that most users suggest the descriptions of questions should be clearer, and the number of pages and items should be appropriate. This study further developed the context of users' filling in online forms including affinity diagram and flow model, and proposed online form design guidelines.