Abstract: Considering the block in upstream storage and high throughput in downstream refineries, the Phase Ⅱ improvement will be carried out on China West Crude Oil Pipeline to enlarge the throughput, namely, some oil pumps are equipped with larger impellers. The pipeline operations before and after the improvement are analyzed, showing problems in operation under low throughput (lower than 1 800 m³/h) after improvement, such as difficulty in pump configuration, and excess consumption in throttling and power. It is recommended to carry out sufficient assessment and research on pipeline operation before the improvement. The test of pumps with large impellers operating under low throughput of 1 800~2 000 m³/h shows that the pumps can operate normally under low throughput. The changes of some related parameters are analyzed with different testing methods and then the best timing of testing on pumps with large impellers is proposed. The test on the whole line operating continuously under large throughput shows that the operation of some pumps with large impellers can effectively reduce the power consumption and increase the number of standby pumps. Moreover, the Phase Ⅰ and Phase Ⅱ adaptive throughputs of oil pumps are put forward, providing guarantee for the safe and economic operation of pipeline under large throughput.