Abstract: Piezoelectric loudspeakers are used in thermoacoustic refrigerators for miniaturizing the system because of the high operating frequency. Then the matching between the piezoelectric loudspeaker and resonant pipe becomes an important factor for improving the system performances. By the equivalent circuit model, the expressions of the output acoustic power and electroacoustic transfer efficiency are obtained, and then the structures of the piezoelectric loudspeaker and resonant pipe, as well as the operating frequency are optimized to obtain high electroacoustic transfer efficiency and acoustic output power. It is also shown that the resonance frequency of the resonant pipe is the optimized operating frequency and a high acoustic output power can be achieved when the total reactance of the system equals zero. However, the highest transfer efficiency and largest acoustic power cannot be obtained simultaneously, therefore a trade-off condition must be adopted.