The invention discloses a safety distance warning device and a warning method for specifying welding and cutting operations. The device comprises a device I, a device II and a device III; the device I is arranged on a bottle body frame of one of an oxygen bottle and an acetylene bottle; the device II is arranged on the other bottle body frame; the device III is movably arranged on a welding gun; the device I includes a signal emitter I and an emitter III for bluetooth wireless transmission; the device II includes a receiver III, an emitter II and a warner I for bluetooth signal transmission; the device III includes a receiver I, a receiver II and a warner II for bluetooth signal transmission; the emitter I is in bluetooth connection with the receiver I; the emitter II is in bluetooth connection with the receiver II; the emitter III is in bluetooth connection with the receiver III; the receiver III and the warner I are in circuit connection; and the receiver I, the receiver II and the warner II are in circuit connection. Compared with a traditional unmanned monitoring or manual distance measurement welding operation mode, the device can automatically monitor safety distances between related equipment and give an alarm, and is high in safety.