Abstract: Randomized controlled trial （RCT） is so far considered as an important way to provide evidence to make up therapeutic strategy. However, sometimes it is limited to represent the authentic condition during clinical practice. Whereas, Real world study（RWS）, a kind of observational studies, is applied to present the real world population through analysis of “real world sample”. RCT pays more attention to efficacy trials. While RWS more concentrates on effectiveness trials. RWS requires giving propensity scores to decrease covariant malconformation among groups. In the past few years, RWS has been increasingly applied in clinical studies to integrate experience medicine with evidence-based medicine. Results of RCT need to be tested and expanded forward in real world study. Therefore, comprehensive evaluations by both RCT and RWS are supposed to be the best selection.