This work is concerned with a numerical method by using parametric spline function to solve the coupled Klein–Gordon–Schrödinger(KGS) equations. The fourth‐order accuracy scheme of space can be obtained by selecting appropriate parameters. The stability analysis of the scheme was studied by using von Neumann technology. This method has no restrictions on time step rationing. The validity and accuracy of the method are demonstrated by numerical examples. Numerical simulations were carried out to prove the advantages of the method.