The dendrimers used here are poly-(amidoamine) (PAMAM) dendrimers (Generation 1) (Aldrich Incorp. USA). CF unsizing and oxidation process is similar to a previous report [5]. The CNTs just need to be treated to attach carboxylic groups as usual [5]. The oxidized CFs with the carboxyl groups are put into the methanol solution of PAMAM at 22±2 °C for 12 h. The functionalized fibers are then rinsed with methanol and dried in vacuum at 50 °C for 1 h. As a result, a nano-patterned dendrimer layer is adsorbed onto the CF surface and a large amount of amino groups covers the CF surface. In order to get different adsorption densities, the feeding ratios by weight of CF:PAMAM can change from 1:0.2×10−4 to 1:5×10−4. Subsequently, 1 mg of the treated CNTs is dispersed in a 50 ml acetone solvent with an ultrasound bath at 50 °C for 1 h. A 5 mg amino-functionalized CF is dipped into the CNTs suspension for 12 h, followed by a heat treatment at 100 °C. After acetonewashing in an ultrasound bath, the CNT/CF multi-scale reinforcement (MSR) is finalized. The experimental scheme is shown in Fig. 1. Compared with other methods [1–7], it simplifies processing [1–6], avoid the toxic acyl chlorination processing[5] or catalyst contamination[1–4] and increases controllability and effectivity [7]. The chemical reactions are confirmed by XPS ( PHI 5700 ESCA) and FTIR (Bruker Tensor 27). The surface microstructures are observed by SEM (S-4800, Hitachi, Japan).