With ab initio theory and elastic scattering Green's function method, electronic structure, conductance and current of 1,4-phenylene diisocyanide molecule are investigated. It shows that charge of system is transferred and redistributed by electric field. Electron gathering area and dissipation area are formed near interface between molecule and electrodes. Additional electric dipoles are formed, which restrain conductance and current of molecule. Moreover, molecular orbit energy and coupling coefficients between molecule and electrodes are influenced obviously by electric field, which make differences in molecular voltage current characteristic.