The utility model relates to a deviation rectifying and alarming device of a girder transporting vehicle. The device comprises an ultrasonic sensor, a single-chip microcomputer and an alarm, the ultrasonic sensor is installed on a supporting leg of the girder transporting vehicle through a support, the output end of the ultrasonic sensor is connected with the input end of the single-chip microcomputer, and the output end of the single-chip microcomputer is connected into the alarm and an LCD. The support is made of channel steel, long holes and short holes are formed in the two ends of the channel steel, the long holes are fixed to the outer sides of the supporting legs, and the ultrasonic sensors are fastened in the short holes. The beneficial effects of the utility model are that: the utility model discloses: the beneficial effect is: Ultrasonic sensors installed on supports on the outer sides of four supporting legs of the beam transporting vehicle are used for detecting the distances between obstacles on the left side and the right side of the beam transporting vehicle. The distance value between the girder transporting vehicle and the obstacle is displayed through the LCD, andwhen it is judged that the numerical value deviates from the design value (in a dangerous distance), the alarm gives an audible and visual alarm to remind a driver to correct the direction of the girder transporting vehicle, thereby solving the problem of insufficient sight of the driver and ensuring safe driving of the girder transporting vehicle.