The application of non-contact laser ultrasonic technology in the metallurgical quality inspection and evaluation of laser additively manufactured (LAM) key metal components for aerospace has been widely studied and concerned. This technology can stimulate multi-mode ultrasonic waves by using a single pulsed laser excitation. Therefore, different metallurgical characteristics such as microstructures, defects, and residual stress can be detected and evaluated by analyzing the changes of characteristic parameters of ultrasonic waves in different modes. This paper focuses on the research progress of laser ultrasonic technology in detecting metal LAM defects, such as coarse grains, voids, cracks, and surface residual stress. The aim is to address challenges related to microstructural grain size assessment in strong-scattering material, online detection of micro-defects on rough surfaces, and high-precision characterization of surface residual stress under complex LAM environments involving high temperature, high pressure, and vibration. The main problems existing in the current research are analyzed. The results provide a reference for the future application of laser ultrasonic technology in the online detection of metal LAM metallurgical quality.