The Taylor series of Melnikov function is used to study the bifurcation of nonlinear systems with high codimension in this paper. The method is approved feasible by analyzing the generalized codimension-4 Duffing-Van der Pol equation. The results shown that there is the phenomena of multiple limit cycles, limit cycle and heteroclinic loop, heteroclinic loop are possible. Finally the numerical solutions are given to show that the analysis results are correct.