In high-temperature conditions (over 50℃), hydrocarbon-degradable microbial consortia were isolated into 3 strains, of which each name was Geobacillus subterraneus OH1, Brevibacillus agri OH2, and Geobacillus vulcani OH3respectively. The isolated microbes were injected into two oil-contaminated sites in which each in situ thermal desorption (ISTD) and soil vapor extraction (SVE) was being operated. After 287 days operation, the biological reduction of hydrocarbons as TPH (Total Petroleum Hydrocarbons) in ISTD zone was found higher than in SVE zone. Population and activities of soil microbes also were higher in ISTD zone, which showed that the injected thermophilic microbes in ISTD zone survived well even in high- temperature conditions and more contributed to the reduction of soil TPH than in SVE zone.