A long core physical simulation system(800 cm) was applied to study the indigenous microorganism flooding on a block of Xinjiang Oilfield.Tracking measurement was investigated on the variation of microorganism,nutrition and metabolite.The activation result was different at different position which could be approximately divided into three parts,such as oxygen-enriched part,oxygen-lacked part and anaerobic part.The results showed that the cell population of aerobic bacteria was different at different position in the porous medium and that of the aerobic position was obviously higher than that of anaerobic position.There was no regularity about the surface tension at different sample points,and the measured value had ups and downs.The surface tension of culture medium reduced from 57.7 mN/m to the lowest value 41.51 mN/m.The cell population,total content of organic carbon and total content of nitrogen increased first and then decreased with increasing output of produced fluids.The cell population of probiotics had a large scale enhancement,and that of the sulfate-reducing bacteria was inhibited efficiently.The ultimate recovery increased by 5.84% OOIP.The indigenous microorganism was activated efficiently in simulated oil-bearing formation,and the results reflected the succession from aerobic to anaerobic microorganism in reservoir,which indicated that the flooding effect and development prospect of enhanced oil recovery employing indigenous microorganism was good.