Abstract: To solve the problems of low efficiency and imbalanced duplex phase proportion of weld seam caused by complex thermal cycles in traditional arc welding of duplex stainless steel, a novel high-efficiency magnetically controlled laser-MIG hybrid welding technology for 2507 super duplex stainless steel was proposed. Xiris camera and high-speed imaging system were used to systematically study the plasma morphology and droplet transfer mode under different excitation parameters to elucidate the action mechanism of external excitation magnetic field in laser-MIG hybrid welding process. The results indicate that the addition of an external magnetic field changes the force state of plasma and droplet, thereby changing the plasma morphology and droplet transfer mode. Within a certain range, the applied external magnetic field can effectively regulate the plasma morphology, accelerate the droplet transfer frequency, simultaneously improve the droplet transfer stability, and improve the weld formation quality. When the excitation current is 1.0 A, and the excitation frequency is 75 Hz, the plasma presents a stably burning “bell shape”; the droplet transfer mode is stable jet transfer, and the weld formation quality is optimal.