The oral route for delivery of pharmaceuticals is widely used and accepted. However, many biological therapeutics that have poor solubility, poor permeability, and/or poor stability in the gastrointestinal environment have poor oral bioavailability and are therefore rarely used for oral drug delivery. In recent years, nanocarriers are widely used, which can provide an alternative solution for oral administration of these drugs. In this article, several nanocarriers (nanoparticles, micelles, liposomes, nanocrystals, carbon nanotubes, nanoemulsions, dendrimers, and nanospheres) for drug delivery systems have been designed based on different nanomaterials for oral drug delivery.