<p>Selective laser melting (SLM) is a complex thermal–mechanical coupling process. During the forming process, a large temperature gradient and thermal stresses will be generated inside the formed part, causing warping deformation. In view of the above problems, the thermal–mechanical coupling mechanism of SLM forming process is studied by taking 316L stainless steel SLM formed thin-walled parts as the research object. According to the theory of heat transfer and thermal elastic-plasticity, the temperature field and stress field of SLM forming process are analyzed. Based on this, the related equations of thermal–mechanical coupling in the forming process are derived. Then, the SLM forming process of the 316L stainless steel is simulated, and the temperature field distribution characteristics of the formed parts at different times are obtained. The temperature variation of each monitoring point is analyzed, and the effects of different laser powers, scanning speeds and scanning spacings on the temperature field and residual stress of the formed parts are studied. It provides a theoretical basis for improving the forming accuracy and structural performance of the SLM formed parts, and enriches the theoretical results of the thermal–mechanical coupling effect in the SLM forming process.</p> Graphical Abstract <p></p>