DK376+238~+306 section of Yangjiaba tunnel on LanzhouChongqing railway passes underneath Yanligou debris flow gully under a shallow cover. If the tunnel section mentioned is constructed by mining method, incidents, such as crown collapse, mud burst and water burst, may occur. If the tunnel section mentioned is constructed by cut and cover method, incidents related to deep foundation pit may occur. A new tunnel construction method, which consists of open cut for the arch part, undercutting for the lower part and consolidation for the floor, is adopted so as to avoid the abovementioned incidents. In the end, the tunnel section is built successfully. The paper can provide reference for similar projects in the future.