A precise positioning system for dual stage switching exposure, which includes a base, a first wafer stage positioning unit disposed on the base for a pre-processing workstation, and a second wafer stage positioning unit for an exposure workstation. Each of the wafer stage positioning units includes a wafer stage, a motion positioning detector, an X-direction guide bar, and a Y-direction guide bar. The pre-processing workstation and the exposure workstation both have two X-direction guide bars positioned on and movable along the Y-direction guide bars. The X-direction guide bars of adjacent workstations can be connected to each other.