Disclosed is an ultrasound-guided assistance device for a needle (300), the device comprising: a probe (100) for transmitting and receiving ultrasonic signals for a tissue (600) to be punctured and injected; a first robot arm (200) for moving the probe (100) to the tissue (600) to be punctured and injected; a second robot arm (400) for fixing the needle (300) for puncturing, moving the needle (300) close to the tissue (600) to be punctured and injected, and then pushing the needle to penetrate the tissue (600) to be punctured and injected; and a host (500) for controlling the first robot arm (200) to move the probe (100) to the tissue (600) to be punctured and injected, wherein the probe (100) transmits and receives ultrasonic signals; the host (500) synthesizes an ultrasonic image based on the ultrasonic signals transferred by the probe (100); the host (500) at least calculates, by means of the ultrasonic image, the puncture distance and the puncture angle of the needle (300) with respect to the tissue (600) to be punctured and injected; and the second robot arm (400) is controlled by the host (500), based on the puncture distance and the puncture angle, to move the needle (300) by the corresponding puncture distance and puncture angle and then perform puncturing. The ultrasound-guided assistance device for a needle (300) is used for guiding accurate puncturing of the needle (300).