Abstract: There are such problems existing in depressant low throughput pipeline as coating aging in outgoing line at depressant station, low temperature corrosion of convection coils in heater at intermediate heating station, pressure rising in trunk-line caused by cold oil head. And relative measures are raised: ① speeds up overhaul schedule on outgoing line at depressant heating station; ② renews and reforms heaters at heating treatment station; ③ prevents cold oil head from outgoing of the station and avoids cold oil mixing up; ④ strengthens tour checking of operating heater and inspecting of convection coils during shut down period; ⑤ stricken quality evaluation on crude oil modifier.