Spectroscopic　measurement　of　methane　gas　concentrations　using　absorption　lines　in　the　near　infra-red　(the　1.67　μm　region)　has　been　demonstrated　by　several　research　teams.　In　this　paper,　a　methane　telemetry　system　based　on　tunable　diode　laser　absorption　spectroscopy　(TDLAS)　is　proposed　and　demonstrated.　The　center　wavelength　of　the　laser　is　locked　to　the　methane　absorption　peak　and　the　second　harmonic　detection　technology　is　used　to　realize　the　real　time　monitoring　of　the　methane　gas　concentration.　To　receive　more　signal　light　and　enhance　the　signal　to　noise　ratio,　a　lens　and　its　focal　length,　the　spot　size　of　the　reflecting　surface　and　a　filter　plate　are　used　to　optimizing　the　optical　path.　The　experimental　results　show　that　after　optimizing　methane　telemetry　system　the　minimum　detection　limit　can　be　enhance　from　20000　ppm　to　5000　ppm　in　the　distance　of　20　meters.　©　2020　SPIE.