In order to solve the problem of laser laminated lap welding of galvanized sheet for automobile body, a process of rolling a certain exhaust passage on the laminated joint surface of galvanized sheet was put forward, so that a better welding effect could be obtained under zero clearance. The welding quality of zero-gap laminated joints with and without exhaust channels was compared and analyzed from the aspects of weld surface morphology, splash generation, weld microstructure, micro-hardness, and mechanical properties of joints. The results show that the composite exhaust channel with the main exhaust channel depth of 125.0μm and the secondary exhaust channel depth of 32.6μm can be obtained by rolling, and the lap joint with satisfactory appearance and mechanical properties can be obtained at laser power of 2500W and scanning speed of 25mm/s. The research is helpful to improve the laser overlay welding process of body galvanized sheet.