For the time-variant property of bistatic angles in Receiver Centered Region Area in bistatic radar system, it′s difficult to obtain high resolution ISAR image of target in by using the conventional imaging methods.The signal model for bistatic ISAR was presented, then the time-variant property of the bistatic angles and its influence on range envelope and azimuth was analyzed.A Radon-TCDS-Relax super-resolution imaging method was brought up for eliminate the effect from high-order azimuth terms of target motion model in receiver centered areas.The chirp rate and its changing rate corresponding to high-order phase terms in cross range was estimated by the proposed method.Scatterers extracting and imaging were achieved by Radon-TCDS-RELAX and TCD-RID respectively.Accuracy analysis and the experimental results with real data both demonstrate the effectiveness of the proposed method.