The total length of Yuanliangshan tunnel is 11068m, which is a typical karst tunnel and the longest tunnel on ChongqingHuaihua railway. No.2 karst cave filled with silty sand in highpressure water abundant zone has the greatest difficulty in construction among the total 5 large filled karst caves in Yuanliangshan tunnel. Taking the borehole drilling and grouting construction of No.2 cave as an example, the author make analysis on the construction efficiency and discusses the rapid construction technology of borehole drilling and grouting in karst caves filled with silty sand in Yuanliangshan tunnel in terms of grouting parameters, grouting materials, equipment matching and labor organization.