A blood flow control system, tension adjustable instrument and a method are disclosed. The blood flow control system comprises a detecting unit, a computing and a tension adjustable instrument. The detecting unit real-time monitors the biomolecular response condition of a living organ, and the computing unit dynamically controls the tension adjustable instrument to adjust the tension of the blood vessel based on the detecting result. Therefore the blood flow control system can maintain the biomolecular response condition over a predetermined range to reduce the risk of the liver organ being damaged and augment the curability.