Abstract: The application of digital radiography testing technology in the butt welding of titanium alloy small-diameter tubes was analyzed through experiments, with a focus on analyzing the effects of process parameters such as pipe voltage, pipe current, focal length, and magnification on image contrast and resolution. The results indicated that an increase in tube voltage first increased the image contrast and then decreased, while the resolution decreased with an increase in tube voltage. An increase in tube current could simultaneously improve contrast and resolution. Focusing within the range of 500~900 mm could effectively improve image quality, an increase in magnification could improve sensitivity, but excessively high magnification might lead to a decrease in image quality. For titanium alloy plates with a thickness less than 2 mm, the image resolution was difficult to meet the requirements of GB/T35388—2017 standard, but it could be partially improved through compensation principles. For the butt weld of titanium alloy small-diameter tubes with a wall thickness of 1 mm and a diameter of 10 mm, a double wall double image transmission method was adopted. After optimizing the parameters, it could detect point-like pores with a diameter of 0.15 mm and strip-like lack of fusion defects with a length of 0.2 mm, and the detection sensitivity was comparable to the film method.