Abstract: A novel technology of laser-arc double sides welding for aluminum alloy s was explored.The stability welding process and better appearances can be obtained in double sides welding, except of deeper penetration, higher efficiency and lower cost.The effect of welding parameters on the characteristics of the joints was investigated sy stemically.The results showed that with the increase of laser powers, the weld width of both laser side and arc side became broadened, and the degree of an increase of the widths of both laser side and arc side was almost consistent.With the increase of currents, the widths of both laser side and arc side will be enlarged, and the extent of an increase of the width of arc side was more obvious than that of laser side.Whether laser powers or arc currents are augmented, the minimum widths of cross-sections will rise.Moreover, the depth of minimum width will fluctuate with the alteration of heat input.If the heat input increases to some extent, the depth of minimum width is invariant.With the increase of welding rates, the width and depth of double sides welding will fall, and results in the increase of depth-width ratio in laser welding and the reduction of depth-width ratio in arc welding.