 Multi-jet fusion, MJF, technology is an emerging 3D printing method that utilizes polyamide 12, PA12, as its main material, but has limitations due to high cost and inferior performance of printed parts. To address these issues, PA12 glass beads, PA12 GBS, composites were manufactured via MJF, which improved dimensional accuracy, surface roughness, and hardness. Thermal analysis showed that the composite had an enhanced decomposition temperature and char yield compared to neat PA12, but did not improve its flame retardance. The increased flammability of the composite was analyzed, and possible mechanisms were identified. This article was authored by Binbin Guo, Jiaoshu, Chualuo, and others.