Screw type telescopic pen

The utility model discloses a screw type telescopic pen. The screw type telescopic pen comprises a pen rod which is hollow, wherein a core cavity is arranged in the pen rod, a rotation piece is arranged in the core cavity and is hollow, a sliding cavity is arranged in the rotation piece, the outer wall of the rotation piece is provided with a sliding groove which is communicated with the sliding cavity, a piston rod and a pen core are arranged in the sliding cavity, and the pen core is connected on the piston rod. The outer wall of the piston rod is provided with a convex lug which extending out of the sliding groove, the inner wall of the core cavity is provided with inner threads, and an exposed face, extending out of the sliding groove, of the convex lug is provided with outer threads which are matched with the inner threads on the wall of the core cavity. The rotation piece is rotated in the positive direction, the convex lug of the piston rod pushes the pen core spirally along the sliding groove through