A Non-destructive Test(NDT) for steel cord conveyor belts was developed by using an X ray detector array. The principle of X-ray NDT was introduced and a collimator was used to eliminate the X-ray scattering.An acquisition circuit for multi-channel parallel data was designed to achieve real-time data acquisition. The reason for pixel non-uniformity of the linear array detector was discussed and an algorithm to correct the pixel non-uniformity was established.Then a three-segmented correction algorithm with less computation and better correction effect was proposed based on the response model. Experiments show that the spatial resolution of the image is 1.0 mm×1.5 mm and the non-uniformity of the image is below 2.57% for a steel cord conveyor belt with a width of 2 m and a speed of 3 m. Obtained image shows a good gray contrast,and its gray level difference for a 0.5 mm thick steel is about 13.The new NDT has achieved the real-time online monitoring function, and has advantages of intuitive, clear and so on compared with the tester designed by electromagnetic monitoring principles.