Spatial reflected radiation dynamics is studied when a powerful light beam propagates through a nonlinear DFB-structure. The spatial reflected radiation characteristics depending on Bragg detuning and input Gaussian beam parameters are investigated using numerical simulations. The spatial spectrum of the reflected radiation modes is analytically found for the input pulse with a quadratic shape. It is shown that the process of formation of the reflected beam spatial profile is determined by the self-influence effects and the nonlinear Bragg detuning value. The reflected radiation intensity has, as a rule, a ring-shaped structure.