Phyllonorycter mongolicae is a moth of the family Gracillariidae. It is known from the islands of Hokkaidō, Honshū, Kyūshū and Shikoku in Japan.[1]
The wingspan is 5.5–7 mm.
The larvae feed on Quercus crispula, Quercus mongolica and Quercus serrata. They mine the leaves of their host plant.