The relationship among the nuclear quadrupole coupling constants (NQCC),local electric field gradient (EFG) and bonding structure of pentacrythritol tetranitrate (PETN) were studied by means of ab initio and TOWNES-DAILEY theory. The results show that they are in a good agreement with the experiments,and the errors between experiments and theories with RHF method at 3-21G,6-21G and 6-311G levels are within 13.7%. The EFG of N atoms and Z principal axle direction laid in nitrate plane and are perpendicular to N—O single bonds.The population of N atoms are in a agreement with the results of common structure chemistry. The two methods are complementary each other and the relationship between PETN molecular structure and the nuclear quadrupole resonance parameters of ¹⁴N atoms are described quantitatively.