Based on the empirical electron theory of solids and molecules (EET), the valence electron structure of cementite was calculated and the stable structures of cementite containing Mn and V were determined to be θ -(Fe275Mn025)C and θ -(Fe25V05)C, respectively. The calculated saturation magnetizations (MS) of θ -Fe3C, θ -(Fe25V0 5)C and θ -(Fe275Mn025)C were 16719, 11120 and 14632 A·m2/kg, respectively. The calculated MS, whose error limit is 018%-622%, for the prepared 70-grade and 80-grade tire cord steels with different contents of V and without cold drawing, are in good agreement with the measured values by vibrating sample magnetometer (VSM). The dissolution model with four stages of cementite was built and the influence of cementite dissolution on MS of tire cord steel without cold drawing was attained. The dramatic changes of MS of tire cord steel after cold drawing indicate that the average magnetic moments and the atomic states of Fe in ferrite have changed significantly. The calculation results show that the states of Fe atoms in ferrite would change from hybrid state of A to B or even to C according to the steel′s composition and strain.