In order to develop both cheap and stable ultra-broadband light sources, the output spectral characteristics of ultra-broadband light source based on Bismuth-Erbium co-doped fiber (BEDF) are investigated. With the 830 nm lasers as pump, the output spectrum covers the whole O-, E-, S-, C-, L-bands and the full width at half maximum (FWHM) reaches 525 nm. With the application of BEDF ultra-broadband light source in wavelength division multiplexing fiber Bragg grating (FBG) sensing system, the strain sensing at O band and C band is realized. Experimental results indicate that the application of BEDF ultra-broadband light sources to large-scale FBG network can greatly increase the multiplexing capacity of the sensing system.