The　thermotropic　liquid　crystalline　copolyamide　(TLCPa)/polyamide　66(PA66)　in　situ　composites　was　researched　by　melting　blending.　The　torque　results　show　that　the　viscosity　ratio　of　TLC-Pa/PA66　is　lower　than　unity,　so　the　TLCPa　tends　to　fibrillation　in　PA66　matrix.　Differential　scanning　calorimeter　(DSC)　results　show　that　the　melting　point　and　crystallization　temperature　of　composites　decrease　when　TLCPa　is　added,　and　crystallization　rate　and　the　crystallinity　tend　to　decrease　with　increasing　TLCPa　content,　so　this　system　is　obviously　miscible.　Fourier　transform　infrared　(FTIR)　results　show　that　the　intermolecular　hydrogen　bonding　between　TLCPa　and　PA66　forms　during　blending　process,　and　the　fraction　of　intermolecular　hydrogen　bonding　increases　with　TLCPa　concentrations　increasing.　Scanning　electron　microscope　(SEM)　results　show　that　TLCPa　domains　can　deform　into　fibril　following　simple　shear　flow　during　processing　because　specific　intermolecular　hydrogen　bonding　can　greatly　improve　interfaces　adhesion　of　the　two　components.