The invention provides a construction method of an improved circulating tube in an RH refining furnace. The improved circulating tube comprises an improved upper ring brick and an improved lower ringbrick; by virtue of the construction shape of the improved upper ring brick and a butting opening of the improved upper ring brick and the improved lower ring brick, a square-exterior and circular-interior improved upper ring brick is used for replacing a ramming material filled into the periphery of the original upper ring brick so as to reduce the erosive wear rate and the corrosion rate of theimproved circulating tube, thus the service life of the improved circulating tube in the RH refining furnace is prolonged, and meanwhile the running efficiency of the RH refining furnace is improved as well.