Abstract: In this paper, an improved 2D Fourier domain simulator is presented, which can take the effects of baseline oscillations into account accurately. The phase error caused by baseline oscillation is separated into the azimuth time-variant term and the range space-variant one by Taylor expansion and then is taken into account accurately. The analysis of validity limits shows that this algorithm can be used for the simulation of practical systems. It is accurate and efficient, so it has good application values.