In the research of induced focusing of a beam in self-defocusing media, two-dimensional theoretical model can agree with the three-dimensional experimental results only qualitatively. And there is no three-dimensional theoretical model that can describe the experimental phenomena quantificationally up to now. The transmission of two beams with an angle in the three-dimensional media is discussed. Exactitude derivation of three-dimensional coupled equations is given, and it is found that the description of the beam transmission in this situation is related with the Cauchy problem of the nonlinear coupled equations and the initial conditions of the linear “chatter” phase. The simulative results based on the three-dimensional theoretical model agree with the experimental results quantificationally.