Abstract: Because of its excellent mechanical properties and reinforcing ability, microfibrillated cellulose (MFC) has become a promising candidate for developing nanocomposite. However MFC was easy to agglomerate, which affected its enhancement ability. In this study, MFC was pretreated by freeze-drying(FDMFC). Then FDMFC and linear low density polyethylene (LLDPE) were melted and compounded by a micro-cone twin screw extruder, and the FDMFC/LLDPE composite film was prepared by hot pressing-cold pressing method. The tensile property, dynamic thermomechanical performance (DMA), thermal decomposition process and dispersibility of FDMFC/LLDPE composite were evaluated. The results show that freeze-drying make FDMFC uniformly disperse in LLDPE matrix comparing with the untreated MFC. A reasonable amount of FDMFC can effectively improve the tensile property of FDMFC/LLDPE composite. When adding 10wt% FDMFC, the FDMFC/LLDPE composite increases by 60.3% in tensile strength and 161.9% in Young's modulus comparing to LLDPE. DMA test results show that both storage modulus and loss modulus of the FDMFC/LLDPE composite are improved with the increase of FDMFC content. Thermal analysis indicates that FDMFC can increase the pyrolysis temperature of the FDMFC/LLDPE composite film, and the maximum pyrolysis temperature increases by 14℃ comparing to LLDPE.