Abstract: The current detection of rail welds is carried out manually using portable ultrasonic detectors, which have low detection efficiency and high labor intensity. Due to the influence of the I-shaped structure of the steel rail and the fasteners at the bottom of the rail, automated detection of rail welds has always been difficult to achieve. In order to achieve automated detection of rail welds, a serial scanning function was added to the dual rail ultrasonic detection system. A wheeled probe was used instead of the serial scanning in manual weld detection, which can be carried out simultaneously with the detection of the rail base material. Secondly, a rail bottom scanning equipment using a robotic arm was developed, which also used a wheeled probe and was installed on a dual rail ultrasonic detector. It can achieve rapid detection of the weld seam rail bottom. By utilizing the good coupling of the wheeled probe, the full section automatic detection of the rail weld seam was achieved, and the detection effect was verified in on-site inspection operations. The results showed that the designed automatic detection system can replace manual weld seam detection and significantly improve labor efficiency.