Abstract: Influence of the radial dimension of tubes,especially the resonance tube on the operating frequency of the thermoacoustic Stirling heat engine is described and analyzed using the lumped-element model,and simulated with linear thermoacoustic theory.The analyses and calculation show that changes in the inner diameter of the system tubes,especially the resonance tube,can lead to remarkable change of the operating frequency.Based on the calculation and analyses,we build up a miniature engine with a resonance tube that is only 0.35m in length.Experiments show that,when the resonance tube diameter increases from 15mm to 22mm,the operating frequency changes from 226 Hz to 304 Hz,an increase of 34.5%.This is consistent with the computed result,with errors less than 5%.The experiment also shows that change of the operating frequency leads to the change of performance such as pressure amplitude.This is meaningful for the design and miniaturization of the thermoacoustic Stirling heat engine.