The horizontal overhang is a special overhang structure, and it is also a problem with selective laser melting (SLM) molding technology. This paper studies the relationship between the forming characteristics of the first-layer surface profile features and the forming quality at different laser powers by image processing. The results show that there are bright spots and pores of different sizes on the surface of the first layer by using the “Meander” scanning strategy, which have an angle with the scanning direction and change with the input of laser energy; when the laser power is decrease, the pores on the surface of the layer are enlarged, and the bonding strength between melt tracks becomes lower. The scanning strategy of "rotary" remelting can improve the ability of the first layer to resist external force deformation, and effectively avoid the warping deformation and collapse of the forming surface.