Motivated by the application of (Ti, AI)N alloy compound in the coating layer, the ternary phase diagram of Ti-AI-N was analyzed by the calculation of the phase diagram (CALPHAD) technique. The isothermal sections of the Ti-A1-N ternary system were constructed and compared with the literature experimental results. The thermodynamic parameters of the Ti-A1-N ternary system and the related Ti-N and A1-N binary systems were adopted from literatures, whereas, those of the Ti-AI binary from the literatures were adjusted according to both the ternary and the binary phase equilibria. The consistency between the calculated results and the experimental data shows that considering the ternary thermodynamic relationship, the adjustments to the thermodynamic parameters of the related binaries are necessary.