The paper presents some investigations about the influence of the Nd: YAG laser welding parameters on the penetration and metal evaporation of single and dual pass weld in the case of thin sections of stainless steel sample. The metal loss during welding process was measured in order to establish the optimal values of welding parameters. The geometric size of the welded zone was measured using an SEM microscope in order to establish the correlation between the penetration and width at different values of welding parameters. The microhardness values, measured for 3, 6, 8 and 9 focal point position, in the weld and base material, allow estimating the softening effect caused by the metal vaporization during welding. At the same time, the cooling conditions of the welded zones differ with the local heating and melting volume of the weld.