Methane　is　a　flammable　and　explosive　gas,　which　is　the　main　component　of　natural　gas,　mashgas,　and　biogas.　Using　the　technology　of　tunable　diode　laser　absorption　spectroscopy　(TDLAS)　to　detect　methane,　which　does　not　require　oxygen,　no　poisoning,　no　calibrating,　has　gas　selectivity,　strong　environmental　adaptability,　and　is　stable　and　reliable.　The　laser　transmission　with　the　optical　fiber　has　the　characteristics　of　low　optical　loss,　long　distance　and　flexible　networking.　This　manuscript　demonstrated　an　optical　fiber　laser　methane　detection　device　based　on　TDLAS　and　its　application.　The　laser　was　transmitted　to　the　methane　detection　position　by　optical　fiber,　and　the　laser　interacted　with　methane　in　the　optical　fiber　gas　box.　The　optical　fiber　collimator　coupled　the　surplus　laser　into　the　optical　fiber　and　sent　it　back　to　the　monitoring　device.The　photoelectric　detector　converted　the　surplus　laser　to　an　electrical　signal.　The　monitoring　device　operation　was　based　on　the　principle　of　TDLAS　and　analyzed　the　returned　laser　strength　to　obtain　the　concentration　of　methane.　This　manuscript　described　the　principle,　composition　and　monitoring　spot　network　of　the　fiber　laser　methane　monitoring　device　and　shown　a　practical　application.