Abstract: Statistic analysis about operation parameters and inspection data of an oil pipeline is of importance to safety assessment of a pipeline in service. In this paper, an oil pipeline is investigated and its data is collected about operation pressure and temperature, corrosion inspection, pipeline material performance and so on. For operation pressures and temperatures, statistic characteristic values are obtained by means of statistical analysis and probabilistic distribution types are recommended. For the depth and length of corrosion defects, the exponent distribution and lognormal distribution are recommended, respectively, so that the statistic characteristic values of corrosion defect size are fit from corrosion inspection data. The normal distribution is recommended for performance parameters of pipeline materials as yield strength and tensile strength. It can pass assumption check with confidence level 95%. These statistic results can be fundamental to safety assessment of pipelines in service.