Abstract: The bacterium visbreaking technology is developed aiming at some difficulties found in Ba51 block which are low temperature of formation in low-temperature inspissated pool, high viscosity crude oil and bad effect of using normal waterflooding technology. Experiments are done to separate the bacterium that can affect the heavy asphalt crude oil from residuum pit, to research its metabolic product, and to evaluate its adaptiveness in air temperature. The experimental results show that two kinds of bacterium JH and LC can decrease the surface tension of crude oil by 33%, the viscosity by 68%, which provides reference to applications in future.