The invention discloses a device for monitoring the state of a power transmission line tower-line system, which fully utilizes the advantages of corrosion resistance, wide operation temperature range, anti-electromagnetic interference, passivity, long measuring distance, reliable operation and long service life and the like of optical fiber sensors to configure the optical fiber sensors on a transmission conductor and a tower in a quasi-distributed structure for detecting the temperature, the strain and the acceleration of the transmission conductor and the multipoint stress variation on the tower which are transmitted to an optical modulator demodulator for demodulating and are sent to a computer analyzing and processing system for calculating to obtain the icing quality, the waving amplitude, the breeze vibration amplitude and frequency and the sag of the transmission conductor, and the inclination angle of the tower, thus realizing the simultaneous monitoring on the icing, the waving, the breeze vibration and the sag of the transmission conductor, and the inclination angle state of the tower, and being capable of finishing long-time reliable operation under the on-site severe environment conditions.