Thermosensitive nanoparticles were prepared by self-assembly of two different poly(ε-caprolactone) (PCL) based amphiphilic block copolymers of PEG-PCL and poly(N-isopropylacrylamide)-PCL(PNIPAAm-PCL). The nanoparticles, prepared by dialysis method with different PNIPAAm-PCL contents, showed different physicochemical properties such as lower critical solution temperature (LCST), particle size, and critical aggregation concentration (cac), measured by ¹H-NMR, DSC, dynamic light scattering (DLS), and fluorescence spectroscopy.