Abstract: The digital radiography technology was studied by using amorphous silicon flat plate detector through analyzing the geometry shape and testing requirements of the complex shape steel casting, and results were compared with the conventional film method. The test results show that the detection sensitivity of digital radiography technology meets the requirements of GB/T 5677-2018 and the image resolution and normalized signal-to-noise ratio meet the requirements of GB/T 35388-2017. The test results obtained by digital radiography method and film method are basically consistent, which shows that the detection ability and reliability of X-ray digital radiography method can reach the level of AGFA C7 film method, and can be used for quality control of the steel casting.