FUS exposure with presence of microbubbles can transiently open the BBB at targeted brain tissues. The study purpose is to investigate the dependency of the BBB opening effect with ultrasound exposure time by DCE-MRI. Our result showed extending exposure time can effectively increase FUS-induced BBB opening degree without causing tissue damage. We also proposed a strategy by adjusting exposure time during the multiple exposures to overcome the effects that microbubbles concentration dynamic changed after IV bolus injection. This approach of control FUS exposure time may bring technology advances of FUS-induced BBB opening to deliver drug for CNS disease treatment.