The underwater grouting technology of rubble-mound of a single gravity pier is applied successfully in Qingdao 300 000 DWT crude oil wharf’s construction by the technical measures such as proper configuration of sanded cement grouting without occurrence of segregation using relatively sealed condition formed by soils around closed bedding and caisson installed，use of built-in grouting pipe and construction platform on caisson，proper construction parameters，etc.The rubble-mound foundation can be compacted and its settlement after construction can almost be avoided by underwater grouting，which provide reference for other similar projects.