Abstract: During the quality inspection of BGA solder balls based on X-ray images, existing image processing algorithm can not effectively deal with the images of unexpectedly inclined PCB. A method which could automatically judge the inclination of X-ray images of BGA solder balls and correct them was proposed. The feature of BGA solder balls array was used in the method to rebuild the structural information firstly. Then the transformation matrix between ideal front view image and real inclined image would be calculated by Moore-Penrose generalized inverse matrix. Finally, the inverse matrix of transformation matrix was used to get the ideal front view image. At the same time, the angle of PCB could be estimated by using the transformation matrix. When used in the inclined X-ray images of BGA solder balls, the method could judge the inclination effectively and correct it to get the front view image. The method can be used as an image quality evaluation algorithm to judge whether the image is a desired image in industrial detection, as well as be used as an automatic image correction algorithm to improve the adaptability of the automatic detection system based on X-ray.