The structural stabilities and electronic structures of Nb atomic chains are studied by employing first-principles plane wave pseudopotential method based on the density functional theory. The calculations show that niobium can form planarchains in linear-, zigzag-, dimer- and ladder-form one-dimensional structures. The most stable one among the studied structures are the zigzag-form linear chain, and all the other structures are metastable. The relative structural stabilit y, the electronic energy bands, the density of states and the charge densities a re discussed based on the ab initio calculations and the Jahn-Teller effects.