With the purpose of improving the crystallization rate and toughness of polylactic acid (PLA) comprehensively, chemical modified microfibrillated cellulose (MMFC) and ethylene-glycidyl methacrylate copolymer (EGMA) were used in the preparation of the PLA/MMFC/EGMA composite. After controlled acetylation using acetic anhydride, MMFC exhibited an improved hydrophobicity, resulting in a much better dispersion in PLA matrix. To clarify the impact of MMFC on the crystallization behaviors and mechanical properties of PLA, PLA/MMFC composites with 1-20 wt% of MMFC were characterized using differential scanning calorimetry (DSC) analysis and stress-strain curves. It was revealed that in the presence of only a small amount of MMFC (3 wt%), the crystallization rate of PLA was enlarged for seven times when the crystallization occurred at 120 A degrees C, and the tensile modulus and tensile strength were both increased by 25% compared with pure PLA. The effect of EGMA component on the crystallization and mechanical properties of PLA was considered based on the characterization of the PLA/MMFC/EGMA composite. It was confirmed from DSC thermograms that a small amount of EGMA (5 wt%) did not exhibit any negative impact on the crystallization of PLA in the case of PLA/MMFC-3 wt%/EGMA-5 wt% composite. Meanwhile, in the presence of the EGMA, PLA/MMFC-3 wt%/EGMA-5 wt% composite showed an obvious increase of elongation-at-break from 9.1 to 20.8 compared with pure PLA. A remarkable improvement of crystallization behavior and toughness of PLA was achieved due to cooperative effect of the small amount of MMFC and EGMA in the PLA composite.