Production and storage-transportation of crude oil can not only give rise to soil pollution but also destroy ecological environment. Degradation of microbes for oily soil was studied with the instnunent, Geofina Hydrocarbon Meter (GHM), by experimental analysis qualitatively and quantitatively in the paper. Analytical result showed that the crude oil could be considerably degraded by eating-oil microbes in oily soil and the number of eating-oil microbes increased while the working hours of oil-well rising. As a result, contaminated oil could be degraded more quickly by a lot of eating-oil microbes in the soil. At the same time, the degradation rate of contaminated oil increased gradually as the time went on. In addition, amount of gaseous component in the oily soil samples increased with degraded time and the microbes could selectively consume contaminated oil strongly, so biedegradation might alleviate the degree of contamination and destruction to the soil and environment in the process of oil product