Abstract: This article discusses the character of range-dechirped spotlight SAR signal, analyzes the time and frequency domain character of dechirp SAR signal, presents imaging method of spotlight range-dechirped raw data.The new algorithm combines the advantages of two processing approaches:the efficiency of SPECAN algorithm and the precision of stripmap focusing technique, the first step of the proposed algorithm implements deramp technique representing a simplified version of the SPECAN approach, the second processing carries out the residual focusing via the use of a conventional stripmap processing procedure,in comparison with the range doppler method,this algorithm decreases the processed data with a little amount of calculation increased.The Ku band airborne spotlight SAR imaging experiment confirms its availability.