BrainNet Viewer is a MATLAB-based, graph-theoretical network visualization toolbox designed to illustrate human connectomes as ball-and-stick models. It provides a flexible and user-friendly platform for visualizing brain networks, allowing users to load different combinations of brain surface, node, edge, and volume files. The toolbox offers extensive customization options for adjusting display properties, such as color, size, and layout, and supports multiple views of the brain network. Users can also interact with the visualizations through functions like zooming, rotating, and data cursor. BrainNet Viewer supports exporting figures in various image formats and generating videos. The software is freely available on the NITRC website and has been widely downloaded and used in research. It complements other connectome visualization toolboxes by providing detailed anatomical information and graph-based network demonstrations, making it a valuable resource for understanding the topological properties of brain networks.BrainNet Viewer is a MATLAB-based, graph-theoretical network visualization toolbox designed to illustrate human connectomes as ball-and-stick models. It provides a flexible and user-friendly platform for visualizing brain networks, allowing users to load different combinations of brain surface, node, edge, and volume files. The toolbox offers extensive customization options for adjusting display properties, such as color, size, and layout, and supports multiple views of the brain network. Users can also interact with the visualizations through functions like zooming, rotating, and data cursor. BrainNet Viewer supports exporting figures in various image formats and generating videos. The software is freely available on the NITRC website and has been widely downloaded and used in research. It complements other connectome visualization toolboxes by providing detailed anatomical information and graph-based network demonstrations, making it a valuable resource for understanding the topological properties of brain networks.