The work aims to study the formability and mechanical property of laser metal deposited AlSi10Mg alloy. AlSi10Mg powder with size ranging from 45 to 105 μm was utilized as the material and 6061 aluminum alloy was used as the substrate. Single-layer cladding, thin walls and inclined walls were manufactured with fiber laser in argon chamber to test the formability. The tensile strength and elongation of the walls were tested. The microstructure was analyzed with optical microscope and SEM. There was a positive correlation between the height of single layer and powder feeding speed, but a negative correlation with the scanning speed. Further, the same correlation also existed between the width of single layer and laser power and between the width and the scanning speed. When single-layer wall was deposited, the first 10 layers were not stable. The thickness of wall was thinner than subsequent layers. For the sake of improving the stability and preventing from collapse of walls, laser power should decline gradually in the first 20 layers. With this method, a wall more than 250 layers was made steadily and successfully. AlSi10Mg had good formability when process parameters were selected properly. Inclined walls could be deposited even if the wall had tilted to 60 degree. The porosity of the walls was nearly 3%. The tensile strength was approximately 250 MPa and the elongation was about 5%. The tensile strength was 25% higher than that of ZL104 as-casted aluminum alloy. The microstructure periodically varied along the deposition direction. The eutectic was small and no needle-like eutectic was found. The AlSi10Mg has good formability in laser metal deposition process. The microstructure strength of as-deposited samples is better than as-casted alloy. Finally, a variable cross-section thin-walled sample is deposited with optimized processing parameters.