The paper designed a kind of non destructive detection system of steel rope core based on X-ray. The system takes advantage of good penetrability of X-ray to inspect defects of steel wire rope in belts, uses optical fiber to transmit images information collected on site to remote host computer for analysis and processing, and realizes functions of online intelligent identification and analysis of defect images of steel rope core. Prototype test results show that the system can inspect defects of cut through, puncture, joint twitching, tearing and so on, which improves inspection efficiency and accuracy under the premise of ensuring safety working of X-ray.