The (G'/G)-expansion method is further studied, the solution to the second-order nonlinear auxiliary equation is changed into solving of one unknown quadratic equation and Riccati equation by two function transformations. An infinite sequence solution of auxiliary equation is obtained with the help of Bcklund transformation of Riccati equation and nonlinear superposition formula of the solution. In this way, the infinite sequence solution to the nonlinear evolution equation can be obtained by the (G'/G)-expansion method, this method is an extension of existing methods, which can get more infinite series solutions. Take the (2+1)-dimensional Zakharov-Kuznetsov modified equal width equation as an example to obtain the new infinite sequence solution. This method can be used to get the infinite sequence solution to other nonlinear evolution equations.