Friction force and friction temperature signals were extracted during the friction process. The morphology and structure of phase trajectory obtained from the two signals were analyzed. The morphology was intuitively shown in a three-dimensional space by reconstruction and projection. The structure was characterized by two parameters of average distances between phase points and fractal dimension to show the convergence degree, the complexity and the space-filling ability of phase trajectory. The trajectory analysis demonstrates that the two signals evolve in a similar way. What is more, the evolution is synchronous if two signals are extracted from one friction system.