The system comprises an optical fiber, a light emitting module, an ultrasound detector and an imaging system. The optical fiber has a first end and a second end. The second end of the optical fiber is configured to enter a blood vessel of a human body. The light emitting module emits a laser ray into the first end of the optical fiber, and the laser ray diffuses into a human tissue through the optical fiber to generate an ultrasound signal. The ultrasound detector is disposed corresponding to the second end of the optical fiber for receiving the ultrasound signal. The imaging system is coupled to the ultrasound detector and generates an image with respect to the blood vessel according to the ultrasound signal.
