Based on practice of video-cases teaching， this paper put forwards four sorts of contradictions， which are the contradiction between time limitation of classroom and expressing limi-tation of video cases， the contradiction between relative independence of video cases （part） and con-sistency of teaching objective （entirety）， the contradiction between apparentness of video cases （phe-nomenon） and depth of teaching content （essence） and the contradiction between variability of video case class and control of class by teachers. This paper suggested teaching principle of part conforming to entirety. Meanwhile， it indicated that classroom video case teaching should have strict design， closely coordinated class discussion and teachers should be good at guiding and summarizing. Through these efforts， the above four contradictions can be resolved and designed video case teaching obtained good effect.