Nanofluid is a new kind of working fluid for heat transfer, which can be prepared easily and has higher thermal conductivity than conventional working fluid. It is highly stable compared with suspensions containing micron/millimeter particles and the pressure drop in flow of a nanofluid is nearly the same as that of a conventional fluid. Thus nanofluids are widely used in cooling applications and have great potential for enhancing heat dissipation heat flux. This paper has reviewed applications of nanofluids, preparation and physical properties of nanofluids, effects of nanofluids on boiling heat transfer (including nanoparticles diameter, concentration, wettability and properties of heating surface) and challenges for investigations on boiling heat transfer of nanofluids in the future.