Abstract: In this paper, PIV and thermal infrared camera are used to observe the flow field structure and temperature distribution respectively. In large Prandtl number condition, the critical temperature difference or the corresponding Marangoni number will tend to decrease with the increase of volume ratio and the ratio of height to diameter, besides, the fluid field can flow from stable state via unstable state to oscillation and will change along with the change of high aspect ratio. Traveling wave will appear when the Marangoni number exceeds the critical value, and chaos will follow with higher Marangoni number.