Interaction is very important to all kind of education, including traditional face-to-face classroom lecture and e-Learning. Numerous attempts have been made by researchers to propose some asynchronous interaction methods. Only few studies have so far been made at synchronous ones. Synchronous Office Hour has recently brought to light by some researches. But so far the study of the know-how to conduct it effectively for teachers and students has never been examined. The aim of this paper is to explore the know-how. This research adopts Case Study to collect and analyze representative unique case from NSYSU Cyber University. The case is representative because of the sophisticated teacher, diverse interaction model and enthusiastic discussion. Data collection includes participant observation, deep open interviews, text records, video records, asynchronous board and electronic documents. Data analysis is based on three steps, including pick up key words from different data sources, reorganize the relation of key words and coding. We not only build initial Office Hour framework but also formula the environment setting, execution procedure and interaction model for conducting effective online Office Hour. The most important addition to be made is the value of Synchronous Office Hour to teachers and students.