Abstract: For saving energy with waste heat recovery，thermo-acoustic engine is a promising way due to its simple structure，absence of pollution and low cost. The present experimental study investigated the mechanism of the self-exciting thermo-acoustic oscillation and the forced thermo-acoustic oscillation. In addition，the effects of stack structure and material property on the performance of the thermo-acoustic engine in terms of the critical temperature ratio were examined. It was found that the forced thermo-acoustic oscillation had much lower critical temperature for initiation and the minimal temperature was only 60℃. Ceramic material had better performance than steel and copper and the shorter the stack，the lower the initial temperature for oscillation.