Abstract
In six dimensional spacetime, we assume that the left-handedneutrinos live on the brane. Because the right-handed neutrino is a Standard-Model gauge singlet, it is allowed to propagate in the 5+1 - dimensional world and accrue an infinite tower of Kaluza -Klein excitations. Besides, we will also demonstrate the orbifold relations by the symmetry of the Lagrangian in six dimensions. Using these orbifold relations, we can write down the general Lagrangian and the neutrino mass matrix can be obtained.