We have successfully synthesized large-scale crystalline boron nanowire bundles (BNBs) by chemical vapor deposition method. Fe(3)O(4) nanoparticles were used as catalysts spreading on ceramic substrate during the reaction process. The bundles consisted of many thin boron nanowires with a mean diameter of about 25nm and a length of several micrometers. In addition, boron nanowires are single crystals with an alpha-tetragonal structure and grow along [001] orientation. These nanowires have a surface electron affinity of 3.76eV and a work function of 4.54eV. A turn-on field of 5.1V/mum and a threshold field of 10.5V/mum were found in the nanowire bundles, and stable field emission was recorded at the same time.