In this paper, the applications of nanomaterial in the fields of drilling fluids, completion fluids as well as reservoir protection in recent years were reviewed. The nanomaterials used as nanocomposite filtration-reducing agent, nanocomposite viscosifier, nanosized lubricant, nano-cement slurry, nano-spacer, nanomaterials for reservoir protection, and so on, were introduced, which had played an essential role in maintaining borehole stability, improving cementing quality and protecting reservoir. Finally, the further application of nanomaterial in drilling/completion fluids and reservoir protection is also prospected.