Noise radar has low probability of intercept and high resistance to electronic coun- termeasures, and has the ability of non-ambiguous measurement of range and velocity. Circu- lar SAR (CSAR) has high two-dimensional (2D) ground range resolution and a certain three- dimensional (3D) imaging capability. The combination between noise radar and CSAR can achieve the complementary strengths, which has significance for target detection and high reso- lution imaging. In this paper, Ulam mapping chaotic frequency modulation (FM) signal is used as the transmitted signals for 2D and 3D CSAR imaging. All imaging results are compared with other imaging results when the transmitted signals are chirp and Ulam mapping chaotic ampli- tude modulation (AM) signals respectively. Simulation results of point-target show that when the transmitted signal is Ulam mapping chaotic FM signal, 2D and 3D resolution are higher and side-lobes except integral sidelobe ratio in height are lower than results of other two kinds of transmitted signals, because the effective bandwidth of Ulam mapping chaotic FM signal is wider than chirp and Ulam mapping chaotic AM signals. In addition, Ulam mapping chaotic AM and FM signals for CSAR imaging have stronger anti-interference ability than chirp signal.