The particle size and processability of the powder are the keys for successful nylon in selective laser sintering (SLS) 3D printing, but the nylon powders on the market have disadvantages such as uncontrollable particle size and large distribution, poor sphericity, and poor processability. In this study, graphene oxidehybridized polyamide 6 (PA6/GO) microspheres perfectly suitable for SLS 3D printing have been fabricated via reaction-induced phase separation. The selective distribution of GO in PA6 microspheres was characterized by thermogravimetric (TG) and transmission electron microscopy (TEM), and the particle size and morphology of PA6/GO microspheres could be effectively controlled by adjusting the ratio of caprolactam and polystyrene. Wherein, when the polystyrene addition amount is 15 wt%, the particle size of the PA6/GO microspheres is between 40 and 50 μm, and the sintering window and thermal stability of the microspheres are significantly improved. These experimental results are surprising for the preparation of new nylon SLS 3D printing materials.