Cellulose nanocrystal (CNC) has been widely added to various resin matrix forming resin-based composites because of its mickle inherent advantages, but solving the agglomeration problem and making uniform dispersion of the CNC feasible still remain challenging. In the present work, methacrylic was grafted onto the surface of CNC via a simple esterification reaction. Successful modification of the CNC was confirmed by solid-state C-13 nuclear magnetic resonance (C-13 NMR) spectrum and Fourier transform infrared analysis. The modified CNC powder (CNC-g-MA) exhibited improved thermal stability and good dispersion in chloroform. Moreover, scanning electron microscope microtopographies confirmed that the modified CNC maintained uniformly nanoscaled dispersion in the resin matrix. The mechanical analysis results showed that CNC-g-MA greatly improved the mechanical properties of 3D-printed samples with 43.5% enhancement in tensile strength compared to those only containing raw CNC. The thermal properties of samples were also improved slightly when CNC-g-MA was added due to superior dispersion and affinity with MA resin. Finally, this work paves the way for the feasible modification of CNC as suitable filler in resin-based composites fabricated using 3D stereolithography technology. POLYM. ENG. SCI., 60:782-792, 2020. (c) 2020 Society of Plastics Engineers