In this paper, we construct a new phenomenological isospin dependent global neutron-nucleus optical model potential. Based on the existing experimental data of elastic scattering angular distributions for neutron as projectile, we obtain a set of the isospin dependent global neutron-nucleus optical model potential parameters, which can basically reproduce the experimental data for target nuclei from $^{24}$Mg to $^{242}$Pu with the energy region up to 200 MeV. ; Comment: 35 pages, 12 figures, 3 tables. Discussions and 1 table added, 24 figures removed. Accepted version to appear in NPA