Fatigue fracture is a common failure mode for dissimilar materials friction welding components. To reduce the major accidents caused by sudden fracture of friction welding parts, the paper discussed the feasibility of the combined usage of electric resistance (ER), infrared thermograph (IRT) and acoustic emission (AE) to monitor the critical fatigue damage from the perspectives of energy dissipation and micro defects evolution. The study found that three kinds of signal could be acquired synchronously. They are non-interfering and mutual support. After entering the critical fracture stage, there is a good mapping relationship between ER and the AE ampjavascript:EditorCenter();litude and energy for the specimens of abnormal and normal fracture. They all can be regarded as the parameters of monitoring critical failure. Although IRT is usually used to predict the fatigue limit of materials, but the rapid temperature rising stage may not always be obvious near the fracture. Compared with the single signal monitoring, multi- information fusion has the higher credibility, which is beneficial to increase the service safety and reliability of friction welding parts.