The left branch bridge of Yangtze River's branching channel in Taizhou Bridge project is a 5-span continuous beam bridge with the layout of 87.5m+3×125 m+87.5 m. The diameter of bored piles is 2.0 m, and the length is 94 m. All the piles are constructed by rotary drilling rig. Based on the construction of the bridge, the paper analyses the construction techniques of rotary drilling rig, details the drilling mud, drilling rig's installation, drilling, and summarizes the features and experience, proposing reference for similar project in the future.