Abstract: In western China, oil and gas stations are mostly built on collapsible loess areas. The foundations of the stations and valve rooms have collapses at different degrees which may threaten the normal operation and safety of stations and valve rooms. So, the foundations should be improved. With standard sand, lime, cement and sodium silicate as modified materials, the collapsibility of loess was calculated by varying the proportioning of the modified materials and the compaction coefficient. It is shown that collapsibility of the modified loess is reduced significantly, and even eliminated if the compaction coefficient is set satisfactorily. In terms of modification results, the modified materials can be ranked in a descending order of sodium silicate, lime, cement, and standard sand.