For the PZN-PT-PZ ceramic system, the difference in the temperature characteristics of piezoelectric properties between the tetragonal phase and the rhombohedral one was studied from the viewpoint of a domain reorientation mechanism. From the measurement of thermal expansion and the change of high-temperature X-ray diffraction patterns for two phases, it is considered that the more stable temperature characteristics of the tetragonal phase than those of rhombohedral one originates from the stable temperature dependence of 90-degrees domain reorientation for the poled tetragonal phase. The temperature dependence of dielectric properties is more influenced by 180-degrees domain reversal for both the tetragonal and rhombohedral phase.