The invention discloses an interactive question answering system based on an online class. The system comprises a teacher client end, a teaching progress tracking module, a routine questions database,an extracting module, a plurality of student client ends, a statistic module, an ordering module and a network server, which are interconnected through the Internet. The system is simple in design, during the online class teaching process, routine questions are sent to students for questioning, and the routine questions the students fail to answer and the non-routine questions the students ask are collected, statistic and ordering are conducted, and the questions are answered by the teacher in sequence. Not only are teaching contents of the online class enriched, and question data of the routine questions database expanded, but also the students' learning enthusiasm and learning efficiency are improved, and teaching order of the online class is maintained. The system is high in intellectualization, and good in promotion and advancement effect on education business.