This paper presents a modeling analysis of transient thermoplastic behavior occurring in composite brake disks. A finite element code was developed which allowed an effective investigation of the transient thermoplastic analysis. The results of the finite element analysis presented the pressure distributions and the temperature distributions along the friction surfaces, and heat flux vectors for the present model. The thermoplastic state on any friction surface affected the other friction surfaces each other. Thus, the whole modeling of brake disks was necessary for accurate results. The orthotropic composite brake disks showed better characteristics as a brake friction material than the isotropic ones. The reason is that the composite brake system showed the larger contact regions along the fricting surfaces than the isotropic brake system. The smooth heat flux results in the uniform and the low temperatures and pressure distributions along the friction surfces.