Abstract: Traditional power-frequency fixed speed motor not only wastes electrical energy, but also shortens the maintenance period and service life of pump units when oil flowrate of pipeline is low. To solve the problem, this paper considers that adopting frequency control methods to carry out energy saving is available. The mode of power saving principle of oil pump is that flowrate of centrifugal pump is kept at a constant but the head of centrifugal pump should be cut down. Taking a long-distance pipeline as an example, the testing process of energy saving for oil pump sets with the mode of high-pressure frequency conversion is described. Energy saving effectiveness before and after the installation of frequency conversion device is compared. Results show that after installation of the frequency conversion device, the throttling ratio, power factor and unit efficiency all satisfy the energy saving assessment in limit value and evaluation value specified in SY/T6275-2007, and power fare in 304.5 million CNY from 2008 to 2009 are saved for the whole pipeline.