In this paper, the experimental current density versus electric field characteristics of Si3N4 before and after the electrical field-induced stress were measured. It is shown that, the Frenkel model of Coulomb trap ionization, Hill-Adachi model of overlapping Coulomb traps, Makram-Ebeid and Lannoo multiphonon isolated trap ionization model do not describe the charge transport of Si3N4 before and after the electrical field-induced stress. The Nasyrov-Gritsenko model of phonon assisted tunneling between traps quantitatively describes the hole transport mechanism in Si3N4 before and after the induced stress at traps energies Wt = 1.6 eV and Wopt = 3.2 eV. The current leakage at different induced stresses in Si3N4 is explained by the increase of trap concentration via the creation of Si-Si bonds, which are traps in Si3N4.