The bimicrophone method is an important in situ method to measure the acoustic impedance of acoustic liner,which is going to be investigated in this paper.Because the hole of the honeycomb is too small for microphone to be inserted in,a probe microphone,using a slight probe to lead the pressure out to be measured,is designed.After strictly calibration,the bimicrophone method is used to measure the acoustic impedance of a resonant cavity and a honeycomb perforated liner.And the experiment data are compared with the theoretical results.