Abstract: Based on the model of the airborne tandem bistatic squint synthetic aperture radar (SAR), the extended Loffeld bistatic formula (ELBF) of point target echo is derived by using the weighting factors that is defined by Doppler contribution ratios of transmitter and receiver. Bistatic deformation (BD) term of all point targets (PT) within the imaging scene is substituted by the BD term of centre PT, and residual phase terms in ELBF are expanded using Taylor series expansion to derive the range scaling factor, then the chirp scaling (CS) imaging algorithm based on ELBF of tandem airborne bistatic squint SAR is established. To get accurate focusing result, the BD term is compensated in two-dimensional (2-D) frequency domain and range cell migration (RCM) is corrected by CS method. Considering of the space variance of echo data, data blocking rules in range for wide scene imaging is analyzed. The algorithm utilizes more accurate 2-D frequency spectrum formula, the imaging efficiency is improved by CS method, and the processing procedure is simplified as well. Simulations validate the proposed imaging algorithm to process the data of the tandem airborne bistatic squint SAR.