It is difficult to integrate principles with practice in the teaching of operating systems. We propose a teaching approach  to solve this problem. According to this approach, operating system courses are organized based on the experiments of kernel debugging and analysis. The contents about principles and practice are taught alternately in the teaching procedure while they keep the integrity of their own. The approach can enable students to understand both principles and practice well. Experiments in the past few years show that the approach can help to concretize operating system principles, and make it easier for both teaching and studying.