Objective Quantum chemical calculations based on DFT method was used to study the relationship between the molecular structure and inhibition efficiency of pyrimidine derivatives (DHPMs) used as corrosion inhibitors for carbon steel in acidic media. Methods The quantitative parameters, such as the frontier molecular orbital energy HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), the charge distribution of the studied inhibitors, the absolute electronegativity ( χ) values, dipole moment( μ) and the fraction of electrons (△N) transferred from inhibitors to carbon steel were calculated and correlated with inhibition efficiencies. Results The results showed that the inhibition efficiency of DHPMs increased with the increase in EHOMO, the decrease in ELUMO, the decrease in ELUMO-EHOMO, and the increase in the number of the fraction of electrons (△N) transferred from inhibitors to carbon steel. The areas containing N atoms were the most possible sites for bonding the active sites on the metal iron surface by donating electrons to the metal. Conclusion Compound DHPMI had higher inhibition efficiency than DHPM II, because the pyrimidine ring of DHPMI had stronger electron donating capacity.