For a long time, due to a lack of understanding on microstructure evolution of boron doped diamond (BDD) electrodes in application, there have been controversies on failure mechanism of the electrodes material. In this paper, A BDD coated titanium (Ti/BDD) electrode prepared by arc plasma chemical vapor deposition method was analyzed and accelerated life test (ALT) was carried out in 1 mol/L H2SO4 electrolyte at constant current density of 1A/cm(2). Various analyses techniques were combined to track the electrode failure process. The results showed that during the ALT process, the failure process of the Ti/BDD electrodes may be divided into two stages. In the first stage, defects existed in the coatings may lead to penetration of electrolyte into the BDD coatings, resulting in cracking and delamination of the coatings. Then in the second stage, corrosion of BDD grains and dissolution of intermediate titanium carbide layers occur accompanied by slow coatings delamination. Based on these analyses, possible ways to improve the service life of Ti/BDD electrodes are summarized.