To achieve the teaching effect that the online experimental teaching is essentially equivalent to the offline teaching regardless of time and space limitations, a three stage online experimental teaching mode of “before class, during class and after class” is constructed by taking the online experimental teaching of the modern control theory course as a pilot. This paper expounds the design, flow, implementation and steps, and assessment of online experiment. Through two rounds of teaching practice, the results show that online experimental teaching can help students better understand theoretical knowledge, stimulate the enthusiasm of students in learning, and ensure that students’ engineering practice ability and innovation ability are effectively improved.