The utility model relates to a building disaster escaping device, which is composed of an upper cover, a lower cover, and a slide mechanism of an escape rope. The utility model is characterized in that the slide mechanism of an escape rope comprises a slide wheel of the escape rope and a slide limiting mechanism for the slide wheel of the escape rope, wherein, a sun gear of the slide limiting mechanism is coaxial with the slide wheel, planetary gears which are uniformly distributed on the outer margin of the sun gear are engaged with the sun gear and are also engaged with a big internal gear simultaneously, the upper cover and the lower cover are connected to the big internal gear, and translating friction blocks which are uniformly distributed by dividing block pins on a friction flywheel are installed on the friction flywheel which is connected with the sun gear. The utility model has the characteristics of simple structure, convenient installation and operation, stable performance, safe reliability, etc.