Research conclusions：This paper introduces the main technologies used for construction of Yuanliangshan Tunnel on Chongqing-Huaihua Railway Line and gives the measures for improving the technologies to be used for similar tunnel in future. The tunnel structure is a rarely navicular closed syncline with the features of the all karst developments of ordinary karst tunnel. The construction practice shows the integrated geological prediction in advance, filling construction in high-pressure water-rich karst region, environment monitoring and other key technologies play an important role in successful construction of the tunnel.