Abstract: A model with variable precision rough set (VPRS) was established to predict the fatigue life of aluminum alloy welded joints.The main steps and the key issues were described, and the united entropy-based discretization algorithm and attribute reduction algorithm were used to process the data.The results show that the developed model had high accuracy and coverage with a certain noise tolerance.This method broadens the application of rough set theory and provides a new way to predict the fatigue life of welded joints.