Abstract: Ramie fibre/polypropylene composites were prepared by compression molding process, and the properties of the composites were investigated by comparing the mechanical properties of composites before and after the accelerated thermal aging test at 100℃. The results showed that both the lengths and contents of the fibre had significant effects on the mechanical and melting properties of the composites. Both fibre treated with sodium hydroxide and compatibilizer could improve the mechanical properties and increase the peak melting temperatures of the composites. However，accelerated thermal aging not only decreased the mechanical properties remarkably but also altered both the melting state and the morphologies of the composites greatly.