To realize wide-range optical beam scanning with low sidelobes, we design a multi-circular optical phased array with a minimum spacing of 18 μm between adjacent array elements and an operating wavelength of 1550 nm by optimizing the position of the array elements and the excitation of the array elements using a modified genetic algorithm and a convex optimization algorithm. The optimization is performed in two steps: first, the genetic algorithm is improved to optimize the distribution of ring spacing at a specific elevation angle, which yields a low peak sidelobe level over a wide beam steering range; subsequently, the excitation-amplitude distribution of the array elements is optimized using the convex optimization algorithm for different steering angles, which further reduces the peak sidelobe level. Using this combined optimization, scanning ranges of -45° to 45° and 0° to 360° are achieved in the elevation and azimuth directions, respectively, and the peak sidelobe level reduced to -20.47 dB, with a maximum far-field divergence angle of 0.146°. To verify the effectiveness of the algorithm, a small-scale multi-circular optical phased array containing 64 array elements is developed, and an experimental system is constructed for experimental verification. The experimental results are consistent with the optimization results of the algorithm.