Tunable　diode　laser　absorption　spectroscopy　(TDLAS)　is　a　widely　used　hydrocarbon　gas　sensing　method　in　many　fields.　However,　the　short　scanning　range　limits　its　application　where　multi-species　detection　is　necessary.　In　this　paper,　a　laser　system　based　on　TDLAS　using　a　difference　frequency　generation　laser　was　applied　for　the　investigation　of　the　hydrocarbon　gases　produced　in　the　coal　pyrolysis　process　and　engine　exhaust.　The　coal　sample　was　heated　up　to　623　K　and　the　recorded　spectra　were　analyzed　by　the　comparison　with　the　pure　hydrocarbon　spectra　database.　A　least-squares　fitting　was　performed　to　quantitatively　determine　the　concentration　of　each　component　of　the　mixture.　Totally　nine　different　hydrocarbons　were　identified　and　the　R2　values　close　to　1　indicate　that　the　variance　between　measured　and　fitted　data　was　small.　The　spectra　of　engine　exhaust　were　recorded　and　analyzed　using　the　same　method.　Hydrocarbon　from　C3–C8　and　a　small　amount　of　methane　and　ethene　were　identified.　The　concentration　variation　with　time　was　observed.　©　2021