Based on the first principle density functional theory and perturbation theory, the Exchange Correlation Energy Approximation (GGA) 、Local Density Approximation (LDA) and the pseudo potential approximation (TM) are employed. The relationship between lattice structure and protocell parameters of transition metal iron with 8 outer valence electrons and 16 outer valence electrons is calculated. It is suggested that 3s²3p⁶ should be regarded as the outer electron when calculating the melting temperature of transition metal Fe.