Aiming at the weld seam formation rules and mechanism of 1J79 soft magnetic alloy 0.3 mm thick thin sheet pulsed laser welding, the control experiments of different laser power, pulse width and welding speed are designed. The results show that the thin sheet pulsed laser welding weld is formed by a series of equally spaced weld spots, which is a typical remelting feature. The weld cross section has a fusion line formed by multiple melting. The laser power and pulse width determine the penetration state of the weld, which has a great influence on the front and back surface of the weld and has little effect on the overlap rate of weld spots. The welding speed determines the weld spot overlap rate, which affects weld continuity and weld surface quality. Under the condition of full penetration welding, when the weld spot overlap ratio is more than 62%, a thin sheet pulsed laser welding weld with good shape and uniform surface can be obtained.