Abstract: The imaging quality of the CT system is influenced by many factors. It is necessary to study the influence caused by each factor in order to get a better imaging result. Based on a cone-beam CT system developed by our group, and under the near detector condition, using a standard workpiece of aluminum to study the influences on the imaging quality of CT system, produced by the factors of projection acquisition range and step, tube voltage and current, focal spot size, object position on turntable, beam-hardening correction and image optimizing. The results show that the influence of projection acquisition range on imaging quality is very small, and the smaller acquisition step can improve imaging quality; appropriately increasing the tube voltage can reduce the beam-hardening artifacts and enlarging the tube current can reduce image noise; the smaller focal spot size can enhance the spatial resolution of the image, but was not obvious under the near detector geometry; sample position on turntable does not affect the reconstruction result; hardening correction can greatly eliminate beam-hardening artifacts. Finally, image optimizing can improve image quality effectively. This work provides a reference for the development and application of the CT system.