Abstract: Three-dimensional synthetic aperture radar (3D-SAR) can obtain the three-dimensional resolution of the objects in the observation scene and solve the problems such as layover and shadowing effects of traditional two-dimensional synthetic aperture radar. Different from the existing 3D-SAR imaging geometries, a new 3D-SAR imaging system based on arc surface geometry was designed in this paper. Compared with the existing 3D-SAR imaging system, the system can use arc antenna array to achieve efficient data acquisition and wide view extent. Then, with respect to the designed arc array 3D-SAR system, a three-dimensional wavenumber domain imaging algorithm applied to frequency modulation continuous wave signal was proposed, which can avoid distance approximation and achieve accurate target focus through convolution and interpolation transformation in wavenumber domain. Finally, single-point target and multi-target simulations were carried out. The validity of the designed system and the good imaging performance of the proposed algorithm are validated by comparing the results of our algorithm with the results of the back projection algorithm.