<p>Mechanical contact plays an important role in engineering structures. However, there are no open-source topology optimization codes to design contact structures. Therefore, this paper proposes a new contact topology optimization method using the surface-to-surface frictional contact algorithm. Meanwhile, the complete 499-line MATLAB codes and detailed interpretation are provided in this paper, which is easy to learn and use by junior researchers. The frictional surface-to-surface contact algorithm is briefly described, and the Coulomb friction law is used to model the friction behavior. A frictional contact topology optimization model is established with the compliance as objective function and volume fraction as constraint. The adjoint method is used to obtain the sensitivity of frictional contact problems. Numerical examples compare the effect of different friction coefficients. The proposed method successfully reduces the structural compliance considering the contact boundary, and the increase of friction coefficient is helpful to improve the stiffness of the optimized structures.</p>