Eastern China's crude oil pipeline network is of the largest scale and freight volume in China. Here, we analyze 37 oil pipelines and one railway (38 oil flow channels), 20 oil fields with output of over a million tons of crude oil, and 32 refineries each of which refine over a million tons of crude oil. We construct a supply and demand balance sheet of oil sources and sinks by considering the transportation cost variance of variant pipeline diameters to determine the spatial optimization of Eastern China’s pipeline network. In 2009, the optimal cost of this network was 34.5% lower than the total actual cost, suggesting that oil flow is overall inefficient and there is huge potential to improve flow efficiency. Within Eastern China, the oil flow of the Northeast network was relatively better than others, but the flow in Northern China is inefficient because all pipelines are underload or noload, and there were similar conditions in the Huanghuai region. We assumed no difference in pipeline transport speed, compared to rail or road transportation, thus transportation distance, rather than time, is the main influential factor under the definite transporting cost of variant pipeline diameters.