The invention provides a friction generator based on existing floors. The friction generator comprises common floors and conducting electrodes mounted under the floors and in contact with the floors. The floors are existing wood floors, floor tiles or the floors of other types; the conducting electrodes are made of a metal having high electrical conductivity, such as aluminum, iron, copper, silver and gold, or a semiconductor material. Compared with the traditional power generation floors, the friction generator does not need extra functional materials and devices and only the conducting electrodes are added under the existing floors. The friction generator is simple in manufacturing method, low in cost, easy to manufacture, high in usability and short in production period, and also has high voltage output and strong charging capacity, and thus can be paved by a large batch and a large area. The friction generator can be applied to the fields of security protection and intelligent household, and can be used as a sensor capable of realizing self-driven alarm and initiative monitoring on movable target activities.