The invention discloses a yield loss root cause analysis method based on information fusion, and relates to the technical field of OLED, display, panel and semiconductor manufacturing industry. Aimingat the root cause analysis of yield loss, the invention constructs a problem parameter rapid automatic positioning method and a factor level automatic division method based on information fusion, andsolves the problems of low automation degree, low data information utilization rate and low problem positioning precision of a traditional analysis method. According to the method, the data is labeled and grouped, the pertinence of the data is improved, different rule combinations are designed, the information of reject ratio data and parameter data in all aspects is fused, and the relationship between the reject ratio data and the parameter data is comprehensively considered, so that the positioning analysis of problem parameters is more accurate and efficient. Meanwhile, in order to determine the abnormal fluctuation range of problem parameters, a clustering-based parameter level division method is provided, and the problems that an existing division method is low in speed, low in precision and not beneficial to big data analysis are solved.