An improved model-free adaptive control(IMFAC) approach is proposed for the more general non-affine nonlinear discrete systems. The nonparametric dynamic linearization technique is used in the controller design. By applying the observer strategy, the real-time dynamic linearization for the disturbance systems is realized. Thus the application scope of MFAC approach is extended to the more general non-affine nonlinear discrete-time systems. Then, the robust convergence of the IMFAC algorithm is also addressed. A numerical example is selected to validate the feasibility and effectiveness of the proposed method.