This work is supported by Beijing Higher Education Young Elite Teacher Project (No.YETP0386). 1 INTRODUCTION Society put forward higher requirements for quality of talent with the advent of technological development and the information age. As the talents training base-university, it needs to reform the traditional teaching model and establish new teaching ideas in order to train innovative talents to adapt to the world. Research teaching is proposed precisely conform to the requirements of the times. Compared with traditional teaching, research teaching can greatly stimulate students' interest in knowledge, improve students' enthusiasm and initiative to broaden their horizons and develop students' awareness of innovation as well as develop a scientific spirit and attitude.[1-2] Research teaching has already been the tendency of universities to improve the quality of talents. Research teaching is diverse from formally teaching. Case method is an effective method.[3] The purpose of this method is to encourage students to think, to enable students to grasp the initiative in the classroom and improve learning motivation. Therefore, how can the case be successfully applied to teaching practice? Case selection is critical and the quality of case directly affects teaching effectiveness. The cases which are selected covering knowledge at the same time, not only help students understand the knowledge but also stimulate students' interest. Bayesian formula is an important part of the probability and statistics and is also the core and theory cornerstone in Bayesian statistics. It occupies a very important position in the whole study. The Bayesian formula is applied widely. It has a value of practical application in the financial, internet, medical, engineering and other fields, such as risk assessment, failure diagnosis, forecast and alarm. In traditional teaching, there are some drawbacks: formula complex, difficult to understand, the role of fuzzy, leading students don't know how to apply what they have learned. Therefore, this paper, based on the Bayes formula, discusses the design and practice of the case under the research teaching. 2 THE CASE DESIGN AND PRACTICE OF BAYES FORMULA 2.1 Cancer Diagnosis 2.1.1 Problem Cancer diagnosis is a common example in the textbook, which some scholars have done research on this problem.[4] It spent much time for us on the problem how we have our own characteristic in the teaching design. In order to arouse students' interests and improve the efficiency of learning, we use