With the implementation of the three oil recovery technology, although polymer flooding technology improves the oil recovery, it also brings new challenges to crude oil processing and gathering. High return pressure of oil gathering pipeline was caused by wax deposition of polymer flooding pipeline. Study was carried out on the heat cleaning of the polymer flooding gathering pipeline between the wellhead and the metering room after shutdown the well. The effects of heat washing water quantity, hot wash water temperature and different concentration of polymer on the dredging time were studied under different oil gathering radius. It was found that the hot wash water temperature was more obvious in the range of 65~70 ℃, which was calculated by the theoretical formula. When cleaning different polymer concentration pipelines, in the low water conditions, cleaning time of produced liquid with high concentration polymer was relatively longer. With the increase of heat washing water, there was no obvious change in the cleaning time of the sediment with different concentration.