Abstract: Aluminum alloy thin-walled parts acted as an important component of the aircraft. During the manufacturing process, various types of defects are easily generated. These defects are the main cause of the component failure. Digital Radiography (DR) is an important nondestructive testing technique to ensure the safety of the component. This work investigated the testing process parameters of DR testing. Through adjusting the voltage and current amplitude, the influence of the frame average, voltage and current on quality of the DR defect image was analyzed. From this, the relationship between the image quality (spatial resolution, signal-to-noise ratio and contrast) and the testing parameters (voltage and current) was summarized. Corresponding optimized parameters of DR testing were given. The results provided the guidance on making exposure curve and best parameter selection of DR testing.