A fully-automatic pencil sharpener is provided according to embodiments of the present application, which may avoid the problem of the pencil being overly sharpened in the conventional electric pencil sharpener, and realize a maximized utilization of the length of the pencil, thus is more economical and environmental friendly compared to the conventional electric pencil sharpener. The fully-automatic pencil sharpener according to embodiments of the present application includes a pencil-pushing module, a pencil-sharpening module, a power module, a detection module, a control module and a housing. The pencil-pushing module is adapted to push a pencil to a preset position, for example pushing the pencil to the pencil-sharpening module when the pencil is placed in the pencil sharpener, and pushing the pencil out of the fully-automatic pencil sharpener when the pencil has been sharpened.