Abstract: A large number of karst caves were discovered during the tunnel construction in the Fuxiu second line of the Yuhuai Railway,with high safety risks during the construction.The karst tunnels are classified,and different control measures are taken according to different project conditions,including concrete backfill,steel tube grouting,high pressure jet grouting pile or pile foundation joist(or beam bridge)structure crossing.Well effect of construction is verified according to the site engineering project cases.