AlSi10Mg alloy formed by selective laser melting (SLM) has been gradually applied in aerospace and other fields, and heat treatment can further improve the properties of AlSi10Mg alloy. Therefore, it is very particularly meaningful to explore the effects of heat treatment on microstructure and residual stress of SLM AlSi10Mg alloy. An approach is proposed to evaluate the stress, strain and microstructure changes during heat treatment. As a result, the heating temperature of 350°C and tempering temperature of 200°C are the optimal heat-treatment processes. Furthermore, by tensile fracture analysis, the tensile strength of the sample after heat treatment decreases by 40%, and the total elongation after fracture increases by 280%.