The paper is devoted to propose a method with algorithms which have been written in Matlab language for constructing the numerical solutions for a system of nonlinear differential-difference equations using fourth-order-five-steps Merson’s method. On the other hand, this method has been presented to find the numerical treatment for nth order nonlinear differential-difference equations where Merson method was efficiency for solving nonlinear problems. Comparison between the numerical and exact results has been given for three numerical examples for solving different types of differential-difference equations for conciliated the accuracy of the results of this method.