In order to reform the traditional holistic flooding classroom teaching of Probability Theory, through transforming some concepts, focuses, difficulties, practical applications, and chapter summary and review into microlectures, this paper introduces microlecture teaching under informatization into the classroom. It innovatively explores the microlecture classroom teaching mode, provides preliminary feasible experiences and matters needing attention, allocates microlecture resources outside of class, takes students as the center, effectively stimulates students’ classroom learning interest, improves classroom teaching quality, improves students’ independent learning efficiency after class, realizes normalized “offline+online” microlecture teaching under informatization, and achieves good teaching results.