Disclosed is a self-adaptive pencil feeding mechanism, including: a base, a first pencil feeding assembly, and a second pencil feeding assembly. The first pencil feeding assembly and the second pencil feeding assembly are mounted in the base and are capable of moving to the left or to the right, and the base is connected to a guiding member via an elastic member. The guiding member drives the first pencil feeding assembly and the second pencil feeding assembly to synchronously approach each other inwardly, and the first pencil feeding assembly and the second pencil feeding assembly, when a force caused by insertion of a pencil is applied thereto, are driven by a driving member to synchronously expand outwardly. The self-adaptive pencil feeding mechanism is capable of adapting to pencils of different diameters.