For low flow waxy crude oil pipeline, certain wax thickness retained after wax removal was beneficial to the economic operation of the pipeline for the wax insulation. From the perspective of security, however, certain wax thickness retained was at risk. With certain wax thickness reserved, diameter became smaller. Once the pipeline stopped or output declined, the heat carried by the unit volume of crude oil in the pipeline reduced, and cooling rate accelerated, the formation of the gel structure speeded up. The permitted stoppingtime of pipeline was greatly reduced. The smaller diameter of pipeline was, the more difficult for the pipeline restarted after shutdown . Meanwhile, after shutdown, paraffin deposits destructively slipped in the pipeline lying areas at certain special locations especially acclivities of tube sections, causing the wax plugging. Pigging regularly and thoroughly was recommended.