This paper introduces a novel application of the Wentzel-Kramers-Brillouin (WKB) method to the Schrödinger equation, with the aim of incorporating certain nonlinear modifications that consider gravitational interaction within the wave function. By extending the traditional Schrödinger equation to account for gravitational effects, a new framework emerges, leading to two different sets of nonlinear differential equations for the gravitational potential, denoted as U . It is important to emphasize that these equations exhibit different characteristics and behaviors depending on the sign of U . The main objective of this study is to present a WKB method for the Schrödinger equation, which involves gravitational interactions in the wave function.The authors apply this method to derive two separate nonlinear differential equations for the gravitational potential U , considering both positive and negative values of U. The results reveal the intricate relationship between gravitational interactions and the behavior of the wave function, providing valuable insights into the dynamics of quantum systems under the influence of gravity. The presented WKB method extends our understanding of how gravitational effects affect quantum phenomena. As a novelty in this work, the integration of the WKB method with the Schrödinger equation is shown to address gravitational interactions. This unique approach opens new avenues for exploring quantum systems in the presence of gravity, which could lead to a deeper understanding of the fundamentals of quantum physics. Keywords: Nonlinear Differential Equation, Schrödinger Equation, Successive Approximations, The Wentzel-Kramers-Brillouin Method DOI： https://doi.org/10.35741/issn.0258-2724.58.4.66