The invention discloses an underground sensor network used for expressway life monitoring and a deployment method thereof. The underground sensor network comprises sensing measuring devices, a raster demodulating device, fiber-optic connecting devices, and communication and storage devices. The sensing measuring devices mainly comprise a horizontal strain sensor, a vertical strain sensor, a temperature sensor, and a soil pressure gage. The raster demodulating device comprises a fiber bragg grating demodulation instrument. The fiber-optic connecting devices comprise a fiber junction box, a fiber terminal box, and outdoor optical cables. The communication and storage devices comprise a computer, and a GPRS module. Through embedding fiber bragg grating sensors inside each structural layer of a road, road structure is monitored in a dynamic manner in real time, so that problems that dynamic response of each structural layer of the road on traffic load are solved, difficulties of former monitoring are overcome, and real-time monitoring of road structural information is realized.