This paper presents mainly the nonlinear dynamics of the mechanical system with sectional frictions and combination friction coefficients. It is clear that the nonlinear dynamic characteristics of mechanical systems with sectional frictions are quite different from those of classical machinery, and have more precise and valuable in many practical projects. The expressions of various nonlinear forces are given firstly and the approximation solutions of the system are found with asymptotic method in nonlinear theory, and the combination friction coefficients and damping coefficients of the materials are obtained. Then some nonlinear dynamic characteristics of the system with sectional frictions are also discussed. The results are very important for designers of these machines.