Disclosed is an accurate positioning device of a bridge whole piggy back. The accurate positioning device comprises a three-dimensional bridge adjusting mechanism arranged on a piggy back device of a bearing bridge. The three-dimensional bridge adjusting mechanism and a jacking oil cylinder arranged on the piggy back device jointly bear the bridge. The three-dimensional bridge adjusting mechanism is a three-dimensional adjustable universal oil cylinder. According to the accurate positioning device of the bridge whole piggy back, accurate positioning and displacement of the bridge are achieved by means of the piggy back device, accurate positioning and adjustment can be effectively carried out when the bridge is jacked or dropped down, the number of power auxiliary facilitates in a construction site is reduced, construction difficulty and construction labor intensity are reduced, and construction efficiency and construction accuracy are improved.