Abstract: In long distance pipelines, throttle regulation or other kind of regulation are often performed to pump valves if the real flowrate is lower than what was designed so as to meet the match requirements of the pipeline operation. In theory, power consumption of a pump and the third power of the rotating speed form a direct ratio. If throttling is replaced by speed regulating, its power consumed will decrease by proportion, according to the third power. And the energy saving effect is very obvious. Analysis is done in the paper, on pump efficiency after speed/throttle regulating, comparison calculation is also carried out with the pump of 80Y-100×2 model. Tests for comparison were also done in the laboratory with a centrifugal pump of IS50-32-160 model. The writer did some research on energy saving effect of pumps with variable speed motors and throttle regulation. Large number of data taken from the tests show the result of the tests are in line with the theoretical analysis. Variable speed motors need much less power than that consumed for throttle regulating for the same flowrate. The pump efficiency increases obviously. Much energy can be saved if variable speed motors are widely spread for oil pumps.