The work investigated the influence of laser welding parameters of 304 stainless steel lap joints of various thicknesses on the quality and shape of the weld as well as the mechanical properties of the joints. Experimental studies were carried out based on the standards used in the design, construction and repair of semi-trailers. The welding process was carried out without the use of filler material. The joints were subjected to macrometallographic tests and microhardness tests of the cross-section. The results of joint tensile strength tests with joint shear were carried out and compared with each other. Tensile strength and deformation were determined using the Dantec 3D image correlation system.