In the imagery of synthetic aperture radar with curved track, the traditional hyperbolic range model (HRM) is inaccurate due to the existence of acceleration. Thus, the traditional imaging algorithms of high precision based on HRM such as Omega-K algorithm are no longer available. For this problem, an equivalent HRM which can precisely take the curved track into account is proposed. Then, Omega-K algorithm with some refinements based on this new range model could be used. Simulation results validate the effectiveness of the proposed range model.