An AI-enhanced modal decomposition method is proposed in this paper for fast and efficient high-speed multilayered PCB modeling and integrity. Depending on modal patterns of PCB local structures, modal decomposition method divides a given high-speed PCB interconnections into independent modal cells, and take advantages of different evaluation methods (analytical, numerical, AI-based) to analyze each modal cell. With the assistance of AI technology, compound methods find a way to compute complex PCB structures effectively in this modal decomposition method. We briefly introduced the architecture and workflow of the proposed method, and then gave a practical application example to show the validity. Data show frequency error of 2.3/1.4% and amplitude error of 0.3/0.6dB for 0-28/28-40GHz between measurement and model prediction, showing great potentials of the AI-enhanced modal decomposition method for PCB modeling and signal integrity.