Abstract: The temperature fields of C/C composites braking discs (B757) were studied by the finite element method and experiment，as they were difficult to measure and reveal during the braking process. The loads，boundary conditions and loading processes in the finite element analysis of temperatures were discussed according to the heat t ransfer theory and braking principle of the braking discs. The postprocessing of simulation describes the temperature fields of braking discs during braking clearly and visually. The results show that the temperature of the midial stator rises to the maximum 659℃ at 46s；the temperature of the pressure bearing disk and pressurizing disk rises to the maximum at 48. 5s and the temperature of each test point increases firstly and then decreases in the whole braking process，while the midial stator endures the biggest thermal load，followed by the pressure bearing disk and the pressurizing disk endures the least thermal load. The simulation results are consistent with the experiment data，which verifies the validity of the temperature field results.