Abstract: With an increasing number of oil and gas transmission pipelines being laid across the Loess Plateau region of China,the risk assessment of loess collapse for pipelines that pass through this collapsible loess developed region has become a research hotspot. This study established a matter-element model for loess collapse risk assessment based on matter-element theory and extension set theory (extenics). The model selected 14 representative and quantitative indicators on the basis of surveys and research on regional geological characteristics and collapsibility of loess. Gray correlation method was applied to calculate the weight coefficients of these 14 indicators. The correlation and membership of the matter-elements to be assessed and the risk ranking were determined by correlation function in extension theory. The practical application and comparative studies approved that the application of Gray-Correlation Method-based extenics on risk assessment of loess collapse for oil and gas transmission pipelines is of high reliable and practicable.