Abstract: Laser selective melting forming technology is a kind of additive manufacturing technology for near-net-shape forming without molds.laser selective melting forming technology can realize high precision forming of special-shaped thin-wall parts. Deformation cracking is the most common defect in the SLM forming process of parts. This paper aims to optimize the support addition and placement of parts by combining the problems generated in the practical application of SLM forming;For the test block structure that is connected to a large area of the substrate, a square base can be added at the bottom for transition, and the fillet size can be increased at the same time; The "C-type" corner box can change the commonly used zigzag support into a diagonal strip support, and at the same time make a convex mark on the original surface of the part to be polished; The "I-shaped" corner box enhances the fastness of the combination of parts and substrates by increasing the contact area of the solid support and the surface support, and adjusts the placement Angle to reduce the area of the parts melting layer by layer and reduce the internal thermal stress of the parts. This study provides a reference for designers to design parts and optimize models in the later stage.