Bistatic inverse synthetic aperture radar (ISAR) is an efficient geometric configuration of ISAR and can provide complementary information to monostatic ISAR. However, bistatic ISAR suffers from a serious defocusing problem and distortion problem for maneuvering targets. We propose a method to solve these problems. First, cubic chirplet decomposition based on Keystone transform (KTCCD) is proposed to eliminate the defocusing problem. The echo is assumed as a combination of cubic chirplet atoms, and Keystone transformation is utilized to estimate the parameters for each atom. Then, a method based on distortion term estimation is proposed to eliminate the distortion problem. The distortion terms in certain range bins are expressed by the initial frequency and the chirp rate, and the distortion terms in other range bins are fitted by the ordinary least square algorithm. Simulation results validate the theoretical analysis and show the effectiveness of our method.