ABSTRACTA numerical calculation method based on the angle in a triple junction composed of a random grain boundary is proposed to predict the connectivity and stability of a grain boundary in a B10 copper-nickel alloy. The grain-boundary connectivity and its effect on corrosion resistance are studied combining computer-aided analysis with electrochemical impedance testing. The results show that the prediction of corrosion resistance using a grain-boundary connectivity numerical method is consistent with immersion experimental results. The B10 alloy exhibited the best corrosion resistance after cold rolling with a 9% reduction rate. The relationship between the grain-boundary characteristics and corrosion resistance is well established using the numerical method to quantify the grain-boundary connectivity. A higher connective frequency and a low proportion of grain-boundary angles between 60° and 180° in the triple junction is detrimental to corrosion resistance of the B10 alloy.