The purpose of this study is to investigate the bond behaviour between CFRP plates and corroded steel plates. Double-lap joint specimens with six kinds of corrosion duration and four kinds of adhesive thickness were tested and the primary bond characteristics were analyzed together with the effect of corrosion duration on the surface characteristic. Results showed that the failure mode of the specimens mainly depended on adhesive thickness rather than corrosion duration, only when the adhesive layer take a critical thickness, the failure modes would be significantly affected by corrosion duration, furthermore, corrosion was found to have a positive effect on the ultimate load for the specimens with the same failure mode of steel/adhesive interfacial failure, and the effective bond length of the corroded specimens were obviously larger than that of the un-corroded ones. Results also indicated that as for the specimens of the same corrosion duration, the failure modes changed from the combination of steel/adhesive interfacial failure and CFRP/adhesive interfacial failure to the combination of CFRP/adhesive interfacial failure and CFRP delamination, the ultimate load increased at first and decreased afterwards, and the effective bond length progressively increased with the adhesive thickness increased from 0.5 to 1.0, 1.5 and 2.0 mm.