Abstract. A model for the ion temperature gradient (ITG) driven-instibility is derived from Braginskii magnetohydrodynamic equation of ions. The safety factor in toroidal plasma is introduced into the model through the current density. The effects of safety factor or current density on both the instability in perpendicular and parallel wavenumber spectra and the critical stability thresholds are studied. It is shown that the significant value of the safety factor plays an important role in stabilizing the ITG instability.