In this work, we have successfully exfoliated graphene by electrochemical exfoliation, and then functionalized the EEG flakes via silanization to strengthen the interfacial bonding in CFRP composites. SEM-EDS, FTIR, Raman and XPS elemental analysis not only qualified but also quantified the formed functional groups. In particular, owing to the introduction of C-O-Si and Si-O-Si groups, the content of C-OH decreased from 67.1% (EEG, O 1s) to 13.2% (EEA, O 1s). Lateral size and thickness of both EEG and EEA flakes were analyzed via SEM and AFM, which showed comparable values, thus the effect of aspect ratio could be eliminated during the comparison. Thus, the mechanical performance difference between the EEG and EEA composites is dominated by the silanization.