Abstract: The contact friction problem in structural engineering is very common. Contact synergy makes the solution of nonlinear buckling become more difficulty. From this practical problem, a non-linear finite element equilibrium equation based on the contact interface is build by the finite element method of sub-structure using a cohesion degree of freedom in this paper, and the contact constraint dealt with by the augmented Lagrangian multiplier method is combined with the cylindrical arc-length method combining the problem to track the entire solving process of the nonlinear buckling. The results of number examples show that the contact synergy has a distinct effect to the solving possess of nonlinear buckling, and it is necessary to consider the contact synergy effect in the practical design.