Nonlinear structure of Gaussian laser beam in axial non-uniform underdense collisional plasma is investigated. Due to the combination effect of nonlinear ohmic heating and non-uniform of plasma, and which it modifies electrons temperature and density distribution. On the one hand, due to the effect of the nonlinear ohmic heating, electron temperature and electron density oscillations become highly peaked. On the other hand, due to add the influence of non-uniform of plasma, lead to the departure from sinusoidal shape of electrons temperature, electron density and electromagnetic fields distributions. With the increase of laser intensity, these nonlinear variations become more and more obvious, and their oscillations wavelength decrease.