Aiming at the reference range selection for different antennas in interferometric inverse synthetic aperture radar (InISAR) systems,this paper proposes a respective focusing (RF) method.The reference ranges for echoes of different antennas are selected respectively for RF,which is different from the traditional uniform focusing (UF) with the same reference range applied to all the antennas.First,a comparison between UF and RF for InISAR signal model considering the ranging error is given.Compared with RF,UF has an advantage in overcoming the ranging error differences between different antennas.Then the influence of ranging error upon the interferometric imaging with RF is investigated particularly,and it is found that the ranging error differences between different antennas are far smaller than the wavelength,which is advantageous to imaging.By comparing the capabilities of interferometric imaging between RF and UF,it is concluded that RF is a better choice in conquering problems such as image mismatching and phase ambiguity even with ranging errors.Simulations demonstrate the validity of the proposed method.