In this paper, temperature and pH-sensitive interpenetrating polymer network (IPN) nanogels (NGs) were firstly prepared, and magnetic hybrid NGs were made through in-situ precipitation of Fe 2+ and Fe 3+ into the IPN NGs. Under the optimized condition, the resulting hybrid NG dispersion with up to 17.3 wt% magnetite was stable, while the size distribution of the NGs is broad due to the formation of Fe 3 O 4 nanoparticles outside the NGs. In order to synthesize relatively uniform magnetic NGs, magnetite content was reduced to 8.1 wt% magnetite. The NGs with 8.1 wt% magnetite can quickly self-assemble into colloidal crystals induced by magnet, while such NGs slowly self-assembled into colloidal crystals without external magnetic field. Furthermore, the reflection wavelength of the self-assembled magnetic NGs showed red-shift with increasing pH and temperature.