The 21st century is an era of big data involving all aspects of human life including economics, politics and healthcare. A big-data revolution is under way in health care, starting with the vastly increased supply of electronic medical record system and other healthcare databases. The narrative review will discuss something on the use of big data for clinical researches, by incorporating the author’s experience. The discussion will include several aspects such as limitations of conventional clinical research, the example of big data, conceiving ideas of clinical research and data management. I hope this article will provide new insights into the use of big data for clinical investigators and solicit more brilliant work on this field.