Abstract: Laser welding technology, as a forefront of modern welding research, has been widely adopted in industry. However, the plume generated during the laser welding process interferes with the transmission of laser energy, particularly under high-power conditions, where its absorption of laser energy is significantly enhanced. This leads to difficulties in increasing penetration depth and results in power saturation. This paper reviews existing studies from the perspectives of laser-metal interaction mechanisms, monitoring of the welding plume process, and regulation methods. It indicates that during laser welding, the metal vapor flow inside the keyhole and the metal vapor ejected from the keyhole together constitute a dynamically coupled energy system. Direct observation of the keyhole is challenging due to its location within the molten pool. Current research, based on clarifying the non-uniformity of metal vaporization inside the keyhole, primarily focuses on the external metal vapor–plasma plume system ejected from the keyhole. By capturing real-time optical, acoustic, and electrical signals of the plume through sensors and integrating multi-dimensional characterization methods, the relationship between plasma dynamics and welding parameters can be established. Utilizing tools such as computational neural networks enables the construction of mapping relationships among welding parameters, dynamic plume behavior, and keyhole stability. Key approaches for plume regulation include using pulsed short-wavelength lasers, modulating the ambient medium, adjusting processing environmental pressure or gas composition, and introducing highly ionized inert gases. Future research should focus on clarifying the mechanism by which the plume inside the keyhole affects laser energy, identifying key plume characteristic parameters influencing keyhole stability, and developing more efficient and flexible high-density plume suppression devices to advance high-power laser welding technology.