The utility model discloses a branch is circulation cementing tool for well, including the packing element of center tube and outer suit, have the pressure of confession liquid between packing element and the center tube and get into and outwards push the squeezing clearance of distending packing element, squeezing clearance intercommunication has the biography of the pipe wall that runs through the center tube to press the hole, passes to press to be provided with in the squeezing passageway that hole and squeezing clearance intercommunication formed to supply the liquid stream seat single current switch in the one -way inflow squeezing clearance from inside to outside. The utility model discloses well packing element adopts the mode of squeezing expansion to sit and seals to sit at the packing element and be honored as a queen, along with the decline of suppressing pressure, sit and seal a single current switch and can block the squeezing passageway, in order to keep hydraulic pressure in the squeezing clearance, make the packing element keep sitting the state of sealing, like this the accessible sit seal the single current switch with hydraulic pressure force locking in the squeezing clearance in arbitrary value, can realize in arbitrary position locking with the distending degree of guaranteeing the packing element.