In order to understand the current situation of case study method, the paper firstly makes statistical analysis from a quantitative perspective by using case study papers that have been published in 31kinds of national journals as sample. Secondly, the paper concludes three types of case studies application modes in terms of case function: verified case study, exploratory case study and descriptive case study, and makes a comparative analysis of application modes from five basic aspects. Thirdly, the paper puts forward thirteen key indexes based on literatures, and makes use of key indexes to estimate case study papers of national three representative journals in 2009. Finally, the paper makes some suggestions from the perspective of the development trend of case study method.