Abstract: The solution of the nonlinear contact problem of a large scale structure is a hot and difficult point in current engineering research. In this paper, a new split-step contact solution method is proposed based on the conventional Lagrange multiplier method. The basic principle of the new method is to solve the contact problem in two steps:the first step is to solve the governing equations which are composed of the equilibrium equations of forces of the whole system, and the second step is to solve the constraint equations of the local contact region. In this new method, the Lagrange multiplier is used to accurately simulate the contact constraint conditions, and at the same time, equations are decoupled and the size of equations is greatly reduced compared to the conventional Lagrange multiplier method, making the solution procedure need much less memory storage and easy for parallelization. Moreover, the computational efficiency is further improved by introducing a scaling factor. All these measures make this new proposed method very suitable for solving the large scale structure contact problems. Computational results of the classic Hertz contact case and the plane double seam dam example have verified the correctness of the new method. And the new method was applied to the dynamic analysis of the Yellow-River-Crossing Tunnel global model considering its contact nonlinearity, which further illustrated the efficiency of the new proposed method.