The present invention relates to systems and methods for detecting and visualizing blood vessels. One of the implementations of a blood vessel detecting and visualizing system comprises a sensing device, a processing circuitry, and a visualization device. The sensing device detects a light signal from a blood vessel under the body surface and the blood vessel's surrounding tissues. The processing circuitry differentiates the signal from the blood vessel and the signal from the surrounding tissues and obtains an image of the blood vessel. The visualization device provides a visualization of the blood vessel on the body surface.
