Conventional drinking water treatment has low removal efficiencies for micro-organic pollutants, which made it important to study new technologies of water treatment. The purification efficiency and mechanisms of micro polluted drinking water by Ozone/Immobilized Biological Activated Carbon (O3/IBAC) was investigated. The GAC (Granular Activated Carbon) has become IBAC by using the twelve strains of efficient engineering bacterium. A GC/MS analysis revealed that conventional treatment processes could not remove micro-organic pollutants efficiently. The O3-IBAC has a high performance of the organic pollutants removal. 16 kinds of the organic pollutants have been removed completely after the process of IBAC, and the variety of the typical toxic pollutants has decreased from 6 to 2. The amount of the total organic pollutants of the IBAC effluent has decreased 89.7% while that in the conventional treatment effluent was less than 40%. The safety and health of drinking water can be ensured by the O3-IBAC process.