The utility model discloses a segmented leakage detecting and plugging device for a natural gas pipeline. The device comprises a one-way valve, a second O-shaped sealing ring, a first piston and a protective cylinder, an inner cavity is formed in the inner wall of the protection cylinder, a natural gas circulation hole channel is formed in the inner cavity, a center pipe is arranged on the inner wall of the rubber cylinder, a first piston is arranged on the other side of the center pipe, a supporting gasket is arranged on one side of the first piston, and the supporting gasket and the first piston are connected with a slip. The natural gas pipeline segmented leakage detecting and plugging device runs to a preset position through the packer; hydraulic pressure is applied from the pressurizing channel; hydraulic pressure acts on the piston, so that the piston moves upwards to compress the expansion liquid, the expansion liquid enters the inner cavity of the rubber cylinder through the axial groove of the central pipe, the rubber cylinder expands, the annular space between the rubber cylinder and the inner wall of the pipeline is sealed, the upper connector needs to rotate clockwise to press and release pressure for deblocking, the detection function is easy and convenient to operate, reliability is high, and good economic effects and portability are achieved.