The Generalized Finite Difference Method as a meshless method alternative is used to solve partial differential equations in domains with high irregular geometry. A proof of convergence of GFDM is given studying the consistency of truncation error of linear elliptic partial equation problems at 2D, using n-degree polynomial. As an example, the convergence of method is calculated for a bi-dimentional Poisson equation problem supported over a disperse nodes net representing a rectangular domain.