[en] By using first-principle calculations based on density functional theory, the electronic structures of multi-walled armchair and zigzag boron nitride nanotubes (BNNTs) are investigated. Band shifts between the two layers of the double-walled nanotubes narrow their band gaps and form significant coupling. With the increase of the layer number of the multi-walled BNNTs, the similarity of the electronic structures for the two outer layers is enhanced obviously and the influence of band shift is weakened. Electronic structures of the BNNTs formed with more than three layers are not sensitive to their layer numbers. These results are meaningful for the application researches of BNNTs. Graphical abstract: .