Performance of a pulse tube cooler significantly depends on the efficient operation of its regenerator. Influence of input acoustic power on regenerator’s performance is simulated and analyzed with simple harmonic analysis method. Given regenera-tor’s dimensions and pressure ratio,there is an optimal input acoustic power for achieving a highest coefficient of performance,due to a compromise between relative time-averaged total energy flux in regenerator and relative acoustic power at regenerator’s cold end. Additionally,optimal dimensions of regenerator are also estimated and presented for different input acoustic powers. The computed optimal diameter obviously increases with increase of input acoustic power,while the optimal length decreases slightly,and as a result,a larger input acoustic power requires a smaller aspect ratio (length over diameter). Performance of a pulse tube cooler significantly depends on the efficient operation of its regenerator. Influence of input acoustic power on regenerator’s performance is simulated and analyzed with simple harmonic analysis method. Given regenera tor’s dimensions and pressure ratio, there is an optimal input acoustic power for achieving a highest coefficient of performance, due to a compromise between relative time-averaged total energy flux in regenerator and relative acoustic power at regenerator’s cold end. Additionally, optimal dimensions of regenerator are also estimated and presented for different input acoustic powers. optimal diameter obviously increases with increase of input acoustic power, while the optimal length decreases slightly, and as a result, a larger input acoustic power requires a smaller aspect ratio (length over diameter).