Selective laser melting (SLM) is one of the important additive manufacturing technologies which can produce high quality parts with complex geometry. The main objective of current study is to investigate laser welding of 2 mm thick AlSi10Mg parts fabricated by SLM, and to emphasis on the weld shape, microstructure, pore distribution and hardness of the welded joints. The results show that the cross section of the welds is multi-pass welding appearance, and the cross-sectional area of the welded joints increases from 1.58 mm2 to 3.66 mm2 with increasing heat input from 51 J/mm to 135 J/mm. The increased heat input causes the grain size of the welds to increase from 1.1 μm to 2.5 μm. Circular pores are observed under different heat inputs, and the maximum pore diameter increases from 92.0 μm to 155.4 μm with the increase of heat input. The hardness of the weld zone is lower than that of the base metal, whereas the increase in heat input causes the average hardness to decrease from 86.7 HV to 77.8 HV. These preliminary results demonstrate that it is the feasible to joining SLM AlSi10Mg parts by using laser welding process.