H2O　is　an　important　molecule　in　the　atmosphere,　which　is　closely　related　to　climate　change　and　industrial　applications　(such　as　combustion　process).　The　detection　of　trace　water　vapor　concentration　is　of　great　significance　in　earth　ecology　and　industrial　production.　Tunable　diode　laser　absorption　spectroscopy　(TDLAS)　inverses　the　gas　concentration　by　measuring　the　gas　absorption　spectrum.　The　wavelength　of　the　common　characteristic　absorption　peak　of　H2O　molecule　is　7181.16　cm-1.　The　spectral　absorption　peaks　of　different　wavelengths　are　analyzed　in　the　paper.　It　is　proved　that　when　7306.75　cm-1　characteristic　absorption　peak　is　used　to　replace　7181.16　cm-1　characteristic　absorption　peak　for　concentration　inversion,　the　influence　can　be　reduced　and　the　measurement　accuracy　can　be　improved　by　combining　the　target　peak　with　the　interference　peak.　©　2023　SPIE.