Abstract: Recently,a synthesized highbandwidth technique about multi chirp pulse signal is concerned by the radar  field.This technique can increase the range resolution,while reduce the instantaneous bandwidth and sample rate requirements of radar systems.Against the problem that parameters of the child pulse signal such as data sampling rate,bandwidth,and bandstep may be different,we provide the method of SINC interpolation to reconstruct the uniform sampling signal in this paper,and fulfill the application of synthesized bandwidth technique in SAR by means of fore treatment.At last,the simulation shows that the method is applicable to the multiband child pulse signals with different parameters,and improves the range resolution effectually.