Under the concept of evidence-based medicine, evidence is one of the factors influencing medical practice, among which the original clinical research and the secondary research are the key means to obtain evidence. For the original research, the reliability of the results and the quality of the research are the key to the success or failure of the research. In the process of systematic review or writing guidelines, it is necessary to evaluate the quality and reliability of the original research, and bias risk assessment is one of the core contents. Therefore, the size of clinical research bias risk directly determines the value and impact of research. From this perspective, the self-evaluation of bias risk started at the design stage can help to improve efficiency, reduce waste, and obtain more available original research evidence.