Abstract: An analysis model of aluminum alloy welded joints fatigue data based on information entropy is proposed in this paper. Through calculating and analyzing the information entropy of decision attributes, quantitative contribution of stress concentration, plate thickness and loading mode to the fatigue destruction are researched. The results show that the total information entropy of the fatigue data based on three stress types are respectively 0.997 7, 0.910 0 and 0.817 9. There is consistency between the reducing trend of the weighted information entropy and the declining standard deviation of the S-N curves. In the S-N curve based on the structure stress, the weighted information entropy of membrane stress concentration factor (SCFm) is 0.675 4, which plays a major role in the distribution of fatigue data. In the S-N curve based on the equivalent structure stress, the weighted information entropy of stress ratio is 0.622 3, which indicates that stress ratio is an important factor that influences the distribution of fatigue data.