Abstract: To solve the problem that the boiler water wall tube inspection in power units with scaffolding or lifting platform has a high safety risk and huge cost, a digital radiography（DR） detection system for water wall climbing robot based on remote control was researched and developed with the combination of X-ray flaw detection machine, DR Plate detector and automatic wall climbing robot, while a field DR detection of water wall tube was carried out in a 300 MW coal-fired power unit. Test results show that the detection system has a reliable stability, convenient usability and accurate positioning. This may realize the real-time detection of defects online, and improve the speed and efficiency of detection significantly.