In regard to the pile foundation excavation works of the Lot 1 Guanyinyan Interchange Bridge Project of the Changsha-Yiyang Section Expressway Expansion Project， study was conducted on the oil consumption of a 360 rotary drilling rig in the construction of different diameter pile foundations in this project with consideration of pile diameter， pile length， pile number， engineering quantity， and consumption oil ratio and other factors，， and analysis was made on the causes for the different mechanical oil consumption due to different pile parameters. It was concluded that the pile diameter is the key factor for the increase of mechanical fuel consumption， which has certain guiding significance for the selection of machinery in the pile foundation excavation project and the cost estimation.