Our research found that the Coronavirus infectious bronchitis virus (IBV) nucleocapsid (N) protein consists of two domains: N-terminal domain and C-terminal domain, which are connected by an arginine, serine, alanine rich linker. The N-terminal domain of the IBV N protein exhibits typical RNA-binding protein’s features, with a flexible hairpin loop rich in basic residues and a hydrophobic floor, providing a module for specific interaction with RNA. The C-terminal domain forms a tightly intertwined dimer with an intermolecular four-stranded central ?-sheet platform flanked by a helices. A possible nucleocapsid formation model was proposed that the C-terminal domain forms a helical nucleocapsid scaffold by dimerization and interdimer stacking. The N-terminal domain connects to the helical scaffold by arginine, serine, alanine rich linker and is mainly responsible for RNA binding.