Abstract: According to the statistic reports for evaluation data of oil-gas pipeline performance, the origin of pipeline leakage is summarized. And these origins are collated in sequence in response to the magnitude of resulting average leakage rate, that is, mechanical damage, the third-party interference, natural disaster, maloperation and corrosion. The leakage rate and the polluted area caused by the above origins of leakage are analyzed. The influencing factors in environmental pollution level, such as leakage range, spilling direction of oil at leakage source and location of leakage hole, are presented. And relationship between the size of leakage source and leakage rate is introduced. The analysis results can provide with scientific basis for pipeline maintenance and repair.