The invention relates to an escape device, and especially relates to the building danger escape device comprising an antitheft window buckled on a window; the antitheft window comprises an upper turning sash and a lower turning sash; the lower sash is movably hinged to the window lower edge; the upper sash is movably hinged to the window upper edge; the upper and lower sashes are locked. The escape device also is provided with a one-leg ladder; the top of the one leg ladder is provided with a horizontally telescopic crossbeam, and the outer end of the crossbeam is provided with a hook rod; the escape device is normally arranged on the window to serve as the antitheft window, thus providing antitheft and anti falling effect; in fire danger, the antitheft window can be fast open so as to form an outdoor platform with small interval, so people can conveniently climb down, thus escaping from fire hazard.