The invention discloses a gear-adjustable pencil sharpener. The gear-adjustable pencil sharpener comprises a shell, a driving mechanism, a driven mechanism, a cutting mechanism, a pencil feeding mechanism and a pencil shaving collecting box. The shell comprises a first space and a second space which are partially communicated with each other, a second through hole in a shape similar to an E is formed in the side surface of the shell and comprises a vertical part and four horizontal parts which are all communicated with the vertical part, and four gear slots are formed from top to bottom. The driving mechanism comprises a pressing rod, a first gear set, a tube sleeve and a compression spring. The driven mechanism comprises a rotary shaft, a fixing rod, a fourth gear plate, a first bevel gear and a second bevel gear. The cutting mechanism comprises a cutter rest and a milling cutter. The pencil feeding mechanism comprises a first part, a second part and an elastic element. The pencil shaving collecting box is detachably disposed on the lower portion of the second space. By means of the gear-adjustable pencil sharpener, energy can be stored through the compression spring, the cutting mechanism is driven to rotate around a pencil through the counter-acting force of the compression spring, and therefore the cutting work is finished. The gear-adjustable pencil sharpener has the advantages of being environmentally friendly, capable of saving energy and fast.