Abstract: Objective To observe the inhibitory effects of PEG-APTES-MNP magnetic heating on liver cancer cells. Methods The magnetic nanoparticle complex PEG-APTES-MNP was synthesized and its physiochemical properties and biocompatibility were characterized. HepG2 cells were incubated with the PEG-APTES-MNP nanoparticles for magnetic heating or nanoparticle therapy. Prussian blue staining was used to detect the uptake efficiency of the magnetic nanoparticles by HepG2 cells. MTT assay and flow cytometry were used to evaluate the inhibitory effect of the nanoparticles on HepG2 cells, and laser scanning confocal microscopy was used to detect the production of reactive oxygen species (ROS) in the cells. Fifteen nude mice bearing HepG2 cell xenografts were randomized equally into PEG-APTES-MNP injection group (with nanocomposite injection only), PEG-APTES-MNP magnetic heating group and control group (with PBS injection), and the tumor growth were observed in the mice after the treatments. Results The synthesized PEG-APTES-MNP nanoparticles showed good physicochemical properties and biocompatibility. Incubation of HepG2 with the nanoparticles resulted in significantly increased ROS production, obvious inhibition of the cell growth through the synergetic effects of magnetic heating (P<0.05), and significantly enhanced cell apoptosis. In the tumor-bearing nude mice, the nanoparticles strongly inhibited the tumor growth by magnetic heating (P<0.05). Conclusion The magnetic nanocomposite PEG-APTES-MNP has good physicochemical properties and bioavailability and can strongly inhibit the growth of liver cancer cells both in vitro and in nude mice through magnetic heating, demonstrating its potential as a candidate nanomedicine for liver cancer treatment.