The effects of different kinds of concentration of sizing agent on the performances of carbon fibre and interface of its composites were studied by atomic force microscopy(AFM),and the surface energy along with contact angles was determined by dynamic contact angle analysis test(DCAT) with three different polar liquid.The interfacial shear strengths and hygrothermal ageing of carbon fibres micro-composites was also studied.It was found that the grooves on the 2% sized carbon fiber were disappeared.A significant change in the surface energy of these materials was displayed with the decreased γd and increased γp.The results indicate that the concentration has great effect on the micro-composites interface and ageing properties.The 1.5% sized carbon fibre shows better interfacial adhesion and ageing property than others.