The invention discloses a bottom packer for expandable screen pipe segmenting. The bottom packer is composed of an upper connector, a center pipe, a locking ring pressing cap, a locking ring, a connecting sleeve, a setting sleeve, a locking block, a shear pin, a force transmission key, a force transmission sleeve, an end rubber cylinder, a spacer ring, a main sealing rubber cylinder and a guiding shoe. The bottom packer serves as a pack guiding tool to be applied to the middle segment and the uppermost segment of a sand-proof pipe string of a segmented type expandable screen pipe; the setting sleeve can be downwards pressed while the expandable screen pipe is expanded, the setting sleeve transmits force to the force transmission sleeve through the force transmission key, and the force transmission sleeve compresses the rubber cylinder to achieve tool setting; after tool setting, sealing is established in the annular space; an expandable screen pipe sand-proof system is closed up while each expandable screen pipe communication through way is reserved; and effective sand prevention is achieved, and other tools are allowed to be put down into the expandable screen pipe segment on the lower portion to conduct operation in the later period.