On the basis of Homogeneous balance method,Jacobi elliptic function expansion method and auxiliary equation method,the first elliptic function equation is used to take the solution to nonlinear evolution equation as a new form,and a new periodic solution to Jacobi elliptic function of mBBM equation and KdV equation was constructed with computer algebraic system Mathematica.The method is of universal(significance) in finding the new exact solutions to nonlinear evolution equations.