Abstract: The risk assessment on oil and gas pipeline introduced by W. Kent Muhlbauer is a method of the semi-quantitative risk assessment. This method is easy to learn and convenient for spreading. But the method is in the beginning stage in China. Its theoretical basis and applied technology are imperfect. The fuzzy integrative evaluation is introduced to pipeline risk assessment in order to effectively deal with the subjectivity and uncertainty in scoring. But the relatively risk calculation is not precise. The article introduces the application of gray correlation analysis in the semi-quantitative risk assessment on oil and gas pipeline. First, this paper-analyzes the evaluation indexes (factors) system influencing the pipeline risk, then, establishes the level structural model of the gray integrative evaluation. The integrative evaluation index system of pipeline system risk is made with third party damage, corrosion, design, incorrect operations and the hazard of the medium transported (five indexes system). The weights of different factors are imported in the calculation of the correlation level. And the level analysis and expert scoring of the weight calculation is introduced. The analytical results much more fit the pipeline risk situation because of the application of gray correlation analysis in the semi-quantitative risk assessment on oil and gas pipelines.