An omnidirectional 3D display system is built with the use of scanning LED and cylindrical parallax barrier. To improve image quality, the imaging principle of this system is analysed. The relation between system structure and display parameters, such as resolution, refresh rate and display space, is discussed. A method to increase the resolution is also proposed. Based on the analysis result, an experimental display system is produced. The images have a resolution of 1380 circumferential pixels and 480 vertical pixels, achieving a single-view-angle resolution of 233 pixel×480 pixel within a cylindrical space of 383 mm×480 mm.