The molten structure of Na2O·B2O3 glasses are investigated by the temperature-dependent 11B CW-NMR technique. The results show that, as R≤0.5 there are two stable configurations in the molten state. One configuration, occuring at 730-780℃, has two bridge-oxygen atoms between two boron atoms; and the other configuration, occuring at 880-920℃, has three bridge-atoms between two boron atoms. But only the first configuration exists as R>0.5.