The invention relates to the technical field of bolt non-destructive detecting, and specifically discloses a bolt ultrasonic detecting device.Thebolt ultrasonic detecting device comprises a bolt, anda guiding mechanism is arranged on the outer side of the top end of the bolt, the guiding mechanism comprises an inner rail frame and an outer rail frame, the inner rail frame and the outer rail frameare both of ring structures and are concentrically and parallelly distributed, a plurality of connecting rods are fixedly mounted between the inner rail frame and the outer rail frame, a first rail is mounted on the top of the inner rail frame, a second rail is fixedly mounted on the top end of the outer rail frame, a fixing mechanism is arranged at the bottom of the guiding mechanism,a sliding mechanism is arranged on the top of the guiding mechanism,a clamping mechanism is fixedly mounted on one side of the sliding mechanism, an ultrasonic probe is clamped on the clamping mechanism, and theultrasonic probe is located above the bolt. According to thebolt ultrasonic detecting device,the function of automatic detection is realized, data repeatability is good,detection precision is high, the position of the ultrasonic probe can be adjusted, thus the position of the ultrasonic probe is precisely controlled, and the detection precision is improved.