This study proposes a novel method leveraging low-high frequency cooperative communication to address millimeter-wave communication challenges at complex intersections. Low-frequency communication utilizes channel state information (CSI) for obstacle detection and Line-of-Sight (LoS) prediction, while millimeter-wave communication ensures high-speed, high-precision data transmission. An error prediction and elimination algorithm is introduced to minimize LoS detection inaccuracies and enhance reliability. Simulation experiments at intersections demonstrate improved obstacle detection accuracy and optimized communication performance. This approach advances the applicability of millimeter-wave communication in complex traffic scenarios, contributing to more robust and efficient intelligent transportation systems.