Objective To prepare docetaxel (DTX)-loaded active breast cancer-targeted pH-responsive nanoparticles and to determine its chemo-physical properties, drug loading and releasing characteristics, and targeting ability and cytotoxity against MCF-7 cells. Methods The nanoparticles were synthesized by nanoprecipitation method and surface modification based on polydopamine (PDA). The morphology, size and zeta potential, and surface modification of the nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and X-ray photoelectron spectroscopy (XPS), respectively. Drug loading content, encapsulation efficiency, and in vitro drug release profiles were measured by dialysis and high performance liquid chromatography (HPLC). The in vitro cellular uptake was analyzed by confocal laser scanning microscope (CLSM) and flow cytometry (FCM), and the the effect of drug-loaded nanoparticles on the viability of MCF-7 cells was determined by MTT assays. Results The DTX-loaded nanoparticles, CA-PLGA@PDA-PEG-FA/NPs, exhibited a core-shell structure, with hydrodynamic size of (166.4±3.9) nm, zeta potential of (－11.7±3.8) mV, drug loading efficiency of (9.67±0.45)%, and encapsulation efficiency of (88.32±3.10)%. Furthermore, the drug release rate of the nanoparticles in pH 5.0 release medium was faster than that in pH 7.4. XPS spectra showed that PDA and folic acid were modified on the surface of the nanoparticles. The active targeting nanoparticles ingested by MCP-7 cells were more than the nanoparticles not linked to active targeting ligands, and the cytotoxicity of active-targeted nanoparticles was significantly superior than that of Taxotere^® (clinical preparation of DTX). Conclusion The active breast cancer-targeted pH-responsive nanoparticles (DTX-loaded CA-PLGA@PDA-PEG-FA/NPs) exhibits promising targeting ability and efficient antitumor activity in vitro against MCF-7 cells.