The invention discloses a bidirectional alignment device and method for a slag tank truck. According to the bidirectional alignment device and method, the problems that the traction alignment efficiency of manual guiding a machine head is low and the alignment precision is low. The two-way alignment device for the slag tank truck comprises a vehicle body, a slag tank truck takeover handle, a position detection device, a guide device, walking driving devices and a transmission device. According to the bidirectional alignment device of the slag tank truck, the arranged guide device can limit theleft and right positions of the slag tank truck, so that the vehicle body moves in the guide direction of a guide seat under the guide action of a guide part during operation, and therefore the to-be-aligned slag tank truck can move in the determined direction; and meanwhile, the position detection device is used for limiting the advancing position of the slag tank truck so that the vehicle bodycan accurately pull the slag tank truck to the alignment position, and therefore accurate alignment can be rapidly completed, and the traction alignment efficiency and the alignment precision are greatly improved.