The invention discloses a method and structure for excavating soil in the core tube region based on raft pile supporting. The method comprises the following steps: vertically driving first layer of raft piles one by one on the edge of a foundation pit according to the length and width requirements of the foundation pit and fixing a circle of horizontal timber piles with gate type forcers at one side of the foundation pit of the first layer of raft piles; vertically driving steel ground anchors on the ground outside the first layer of raft piles; tensioning the steel ground anchors and the horizontal timber piles with tie bars; excavating a foundation pit at the inner sides of the first layer of raft piles; vertically driving second layer of raft piles on the edge of the bottom of the foundation pit; fixing a circle of horizontal timber piles with gate type forcers at one side of the foundation pit of the second layer of raft piles; connecting the first layer of raft piles with the second layer of raft piles with tie piles via the gate type forcers; continuously excavating a foundation pit at the inner sides of the second layer of raft piles; driving third layer of raft piles at the bottom of the foundation pit; connecting the second layer of raft piles with the third layer of raft piles with timber piles via the forcers; and doing the rest in the same manner until the foundation pit is excavated to the design depth. The method and the structure have the characteristics of simple and rapid construction and economy.