Since ball-end mill plays an increasing role in machining sculptured surface, it is of great significance to construct the chatter stability lobes for ball-end mill. The precise integration method is proposed in this paper to solve the two order kinetic equation of the milling system considering modal coupling. Based on the condition of the period of delay equal to the single tooth cutting cycle, the instantaneous cutting parts of the cutting edges are determined by the relationship between the contact area and the cutting edge at different time. The Floquet theory is applied to acquire the high precision chatter stability lobes, which are verified by the flat surface machining in the three-axis numerical control (NC) machine tool. The experimental results are in good agreement with the predicted results, indicating the method proposed in this paper can provide the technical support for ball-end milling without chatter.