We explored a novel approach for the modification of titanium surfaces to improve the biocompatibility and antifouling properties using PEG-catechol. As is well-known, PEG-catechol can easily self-assemble onto titanium surfaces. However, the higher grafting density by this approach is hard to obtain. In our paper, o-quinone (the oxide of catechol) as the adhesive segment was used for the first time to graft PEG brushes onto titanium surfaces using the electroreduction process. Variable angle spectroscopic ellipsometer showed that the ultrahigh-density PEG brush adlayer could be grafted to the titanium surface when the o-quinone segment performs electrochemical reduction on the titanium. We called the adlayers that grafted onto the titanium surfaces by this kind of approach, electro-assembly monolayers (e-AMs). This distinguishes it from the PEG-catechol self-assembly monolayers (SAMs). The XPS, AFM and WCA techniques were also used to characterize the coating grafted onto the titanium surfaces via the two different ways. A clear result is that the grafted density of e-AMs can be higher than that of SAMs, and the grafted density of the e-AMs can be easily modulated. In addition, the long-term stability of e-AMs against full blood serum, FITC marked BSA and platelet adsorption was better than that of the SAMs.