A　wavelength　detection　method　based　on　gated　recurrent　unit　(GRU)　network　was　proposed　to　demodulate　the　central　wavelength　of　overlapping　spectra　in　fiber　Bragg　grating　(FBG)　sensor　networks.　The　proposed　method　transformed　the　wavelength　demodulation　problem　of　overlapping　spectra　in　FBG　into　a　regression　problem　and　considered　the　sequence　and　spectrum　characteristics　of　the　spectral　data.　To　learn　the　spectral　data　characteristics　and　train　to　achieve　the　corresponding　wavelength　detection　model,　the　GRU　network　was　used.　Thus,　the　overlapping　spectra　could　be　quickly　and　accurately　demodulated.　Experimental　results　show　that　the　proposed　method　can　overcome　the　precise　demodulation　problem　of　the　central　wavelength　for　partially　or　completely　overlapping　spectra　of　FBG　sensor　networks.　The　test　results　with　root　mean　square　less　than　1　pm　account　for　88.2%　of　the　test　results.　The　detection　accuracy　and　stability　of　the　proposed　method　provide　enhanced　results　compared　with　existing　demodulation　methods.　The　proposed　method　provides　a　novel　way　to　improve　the　multiplexing　capability　of　FBG　sensor　networks.　©　2020,　Chinese　Lasers　Press.　All　right　reserved.