Abstract: This paper presents a bistatic OMEGA-K imaging algorithm based on Fourth-order Extend Exact Transfer Function (EETF4) 2-D spectrum for general bistatic synthetic aperture radar(SAR) data focusing. Applying EETF4, the rang histories of transmitter and receiver are approximated by fourth-order Taylor expansions in azimuth time first. Then the point of stationary phase is derived by solving the polynomial equation which comes from the principle of stationary phase. Subsequently, an accurate bistatic 2-D spectrum is formulated. Based on the expression of the spectrum, a frequency mapping function is derived. Finally a bistatic OMEGA-K imaging algorithm is proposed and the invariance region is analyzed. Simulation results demonstrate the performance of the bistatic OMEGA-K algorithm.