The utility model provides a device is put in to instrument in need not to turn -off fluid loop's return circuit belongs to oil field downhole tool technique, chemical plant installations field. This device is put in to instrument in need not to turn -off fluid loop's return circuit connects on the pipeline, including case, valve body and tee bend, two interfaces of three -way respectively with the pipe connection, form fluid loop, fluid along pipeline and the flow of three -way axis, the lower extreme sealing connection of a three -way third interface and valve body, the case is installed in the valve body it has the valve body to put the thing hole to open on the valve body it has the case to put the thing hole to open on the case, the case is put thing hole and valve body and is put the thing hole and be the through -hole, the valve body can be followed to the case under the effect of drive power axis direction slides in the valve body.