Abstract: Aiming at the problems of using information entropy to evaluate the influence factors of welding fatigue performance, this paper introduces the concept of information gain rate and establishes an analysis model for analyzing the influencing factors of fatigue performance of carbon steel and stainless steel resistance spot welded joints. The information entropy, information entropy proportion and information gain rate of each factor are analyzed to study the influence of each factor on welding fatigue performance. The results show that the information entropy and its proportion of plate thickness and welding time is the largest, and the uncertainty is the highest, however electrode diameter and electrode pressure is just the opposite, the large difference in information entropy of each factor leads to a great influence on the information gain. The information gain rate of electrode diameter and electrode pressure is 59.34%, which has the greatest impact on fatigue performance. The information gain rate of plate width is 38.89%, which has the least impact on fatigue performance. The information gain rate of plate thickness and welding time is 52.33%, the impact on fatigue performance is second to the electrode diameter and electrode pressure.