Thermal dissipation problems in operation process of piezoelectric transformer have seriously limited its development in highpower applications. A threedimensional temperature distribution of a monolayer rectangle piezoelectric transformer was simulated and measured in contour vibration mode in this paper. The experiments with input voltage 60 V，80 V，100 V were setup to compare with simulation result. The simulation result supplemented the experiment temperature distribution influenced by the solder joint position and manufacture process.