After more than 1 000 years of unloading effects, the roof of Beishan Cave 168 at Dazu Rock Carvings is riddled with intersecting cracks, posing significant structural stability problems. At present, the cave roof is temporarily supported by materials like steel plates and pipes, but cracks continue to spread, and the steel plates are severely corroded, leaving the cave at risk of instability and collapse. Emergency reinforcement and protection are urgently needed. Due to the cultural importance of the site, the reinforcement process must minimize disturbance, necessitating continuous monitoring throughout construction. This paper uses numerical simulation to analyze the deformation mechanism under existing support conditions, guiding the placement of monitoring points. Monitoring data from the entire construction process are analyzed to evaluate the engineering treatment. The results provide valuable insights for monitoring and protecting similar structured grotto roofs.