The aim of this study was to investigate the cellular uptake of solid lipid nanoparticles (SLN) and cytotoxicity of its paclitaxel delivery system. The conjugate of octadecylamine-fluorescein isothiocyanate (ODA-FITC) was synthesized, and used as a marker to prepare fluorescent SLN. The cellular uptakes of fluorescent SLN with different lipid material were evaluated by fluorescence microscopy and the measurement of fluorescence intensity. The order of cellular uptake ability was glycerol tristearate SLN>monostearin SLN>stearic acid SLN>Compritol 888 ATO SLN (ATO888 SLN). The cellular cytotoxicities of paclitaxel were highly enhanced by the encapsulation of lipid matrix. Due to the lower drug entrapment efficiency of glycerol tristearate SLN, monostearin SLN was considered as the best lipid material to improve the cytotoxicity of drug. The polyethylene glycol monostearate (PEG-SA) and the synthesized conjugate of folic acid-stearic acid (FA-SA) were further introduced into monostearin SLN, respectively. The PEG and folate modified SLN could enhance the cellular uptake of SLN and the cellular cytotoxicity of drug by the membrane disturb ability of PEG chains on the SLN surface and the improved endocytosis mediated by folate receptor.