Abstract: Based on the imaging geometry of squint mode,the characteristics of echoes in squint mode are analyzed in this paper.The result is that range walk is much larger than range bending,and a modified range-Doppler(RD) algorithm suitable for airborne highly squint mode imaging is derived.This algorithm is based on high-order range model,which firstly corrects range walk in the process of range compression and then corrects range bending in two dimensional frequency domain.The imaged results of simulation and Radar data both demonstrate the feasibility of the algorithm proposed in this paper.