In this paper the perfect Ni2MnGa cluster model is studied by use of the first principles discrete variational method (DVM), which is based on the framework of density- function theory. To study the characteristic properties of the alloy and the influence of the impurities which substitute for Mn at the central, the electronic structure、the binding energy and site energy are calculated. The result illuminates that Ni2MnGa complex obviously has metallic property. Ga plays to transmit electron for the exchange actions between Mn and Mn. And the periodic influence of 11 impurity elements on the binding energy and the site energy is gived. From the microcosmic the reason of the martensitic temperature changed with the concentration of element is analyzed.