The aim of this study is to improve the melt strength of Polylacticacid (PLA) using methylmethacrylate-g-glycidylmethacrylate copolymers, Poly(MMA-g-GMA), that was synthesized by reactive blending at different weight fractions of GMA from 0 to 8 %. Copolymers were blended with polylacticacid (PLA) in internal mixer at different weight fractions from 0% to 15% as chain extender to modify the rheological behavior. The properties of neat PLA and modified PLA were characterized by Gel Permeation Chromatography (GPC), Differential Scanning Calorimetry (DSC) and Rheometric Mechanical Spectrometer (RMS). The balanced torque was increased by increasing the fraction of copolymer chain extender. PLA was even cross-linked when the content of copolymer reached 15%. The number and weight average molecular weights of PLA increased simultaneously as the fraction chain extender was increased. The results showed that Poly(MMA-g-GMA) is an effective chain extender for PLA. The glass transition temperature of PLA was also changed by blending with the synthesized copolymer. The blending affected the cold crystallization behavior and melting behavior of PLA, as well. Dynamic moduli also showed higher viscosities that can lead to higher melt strength. Keywords: PLA; rheological and mechanical properties; reactive blending; P(MMA-g-GMA)