Using　Tunable　Diode　Laser　Absorption　Spectroscopy　(TDLAS）technology　to　accurately　measure　the　oxygen　concentration　in　the　ullage　of　the　aircraft　fuel　tank　is　of　great　significance　to　ensure　the　safety　of　the　aircraft　and　improve　the　working　quality　of　the　aircraft　onboard　inerting　system.　This　paper　focuses　on　designing　a　smart　sensor　for　the　detection　of　oxygen　concentration　applied　to　airborne　inerting　systems,　which　can　reduce　random　environmental　noise　and　line　shape　errors　during　the　flying　process.　First,　a　prototype　including　a　laser　emission　module　with　wavelength　modulation　and　temperature　control,　a　multi-reflection　long　optical　path　absorption　gas　cell,　and　a　high-precision　signal　extraction　module　are　designed.　Then,　ground　experiments　at　294　K,　and　1　bar　are　carried　out.　The　oxygen　inversion　method　is　designed,　the　oxygen　concentration　results　are　obtained,　and　the　lower　detection　limit　(3.3　ppm)　and　detection　accuracy　(9.6　ppm)　of　the　sensor　are　discussed.　Thirdly,　the　change　of　absorption　line　profile　influenced　by　the　change　of　pressure　is　discussed.　The　series　of　oxygen　concentration　measurement　experiments　with　variable　pressure　(274　k,　1–0.1　bar)　was　carried　out.　and　the　measurement　error　is　below　1%.　Finally,　a　second　harmonic　(2f)/first　harmonic　(1f)　normalized　method　is　proposed　to　eliminate　the　errors　caused　by　laser　attenuation　and　environmental　vibration　in　oxygen　measurement.　©　2023　Elsevier　B.V.