A　microchannel　flat　tube-rectangular　corrugated　fin　type　new　internally　cooled　liquid　desiccant　dehumidifier　(NIC-D)　was　designed.　It　was　found　that　the　existing　NTU-Le　heat　and　mass　transfer　model　is　not　well　adapted　to　its　physical　phenomena.　To　respond　to　the　study　gap,　this　study　proposed　a　new　4　NTU-Le　heat　and　mass　transfer　model　based　on　the　physical　characteristics　of　NIC-D　in　the　dehumidification　process.　Through　theoretical　derivation　and　experimental　verification,　the　heat　and　mass　transfer　process　between　air,　liquid　desiccant　and　cooling　water　was　analyzed,　and　the　heat　and　mass　transfer　mechanism　among　the　three　fluids　was　deeply　revealed.　On　this　basis,　a　new　method　for　calculating　heat　and　mass　transfer　coefficients　was　given　in　combination　with　the　model,　which　was　more　adapted　to　the　calculation　of　the　4　NTU-Le　model　in　terms　of　concept.　In　addition,　this　method　summarized　the　correlation　between　heat　and　mass　transfer　from　experimental　data　to　predict　and　characterize　the　performance　of　the　NIC-D　dehumidification　process.　The　results　show　that　the　4　NTU-Le　mathematical　model,　the　new　method　for　calculating　heat　and　mass　transfer　coefficients,　has　high　accuracy,　in　addition　to　the　applicability　of　the　Nu　and　Sh　correlations.　According　to　the　analytical　results　of　the　validation　experiments,　the　errors　between　the　calculated　and　experimental　values　of　air　outlet　temperature,　liquid　desiccant　outlet　temperature,　cooling　water　outlet　temperature,　and　air　outlet　humidity　content　are　within　8.0%,　15.0%,　10.0%,　and　10.0%,　respectively,　and　the　absolute　average　errors　AAD　are　1.73　%,　6.35%,　1.46　%,　and　3.18　%,　respectively.　Decreasing　the　temperature　of　imported　liquid　desiccant　is　a　valuable　way　to　improve　dehumidification　efficiency　and　energy　effectiveness.　For　every　1.0　degrees　C　reduction　in　the　temperature　of　imported　liquid　desiccant,　the　dehumidification　efficiency　and　energy　effectiveness　increased　by　2.6　%　and　1.1　%,　respectively.