Karst caves are common in certain regions of China, and building tunnels through these caves can be challenging. The Yujingshan tunnel in Yunnan Province faced the largest karst cave in Chinese railway history. The main challenges included the cave's huge size, unstable walls, and complex composition. To address these challenges, methods like backfilling the cave, reinforcing the roof, and diverting underground rivers were used. Monitoring showed these methods were effective. This study provides insights for future tunnel construction in similar karst caves.