Premature failure of rock bolt (cable) due to stress corrosion cracking (SCC) is a phenomenon that has reported to occur in underground environments. In this study, the corrosion behavior and failure mechanism of rock bolt (cable) samples obtained from underground coal mine were examined and discussed. Macroscopic observation and weight loss test were carried out for the corrosion characteristics of the bolts without failure. It is found the corrosion form is uniform corrosion for the bolts with short service time (S-1, S-2). But for the bolts with longer service time (S-3, S-4 and S-5), experience different degrees of pitting corrosion and the number of corrosion spots on the surface of the sample increases with increase of the service time. The corrosion amount of different parts of the bolts shows the rule of bolt head > bolt end > free section, and the corrosion amount increases year by year with the service time, but the corrosion growth rate is fast in the early stage and slows down in the later stage. At the same time, the failure mechanism of the failure sample S-6, which has been in service for 6 years, was analyzed with macro and micro methods. The results show that S-6 have been in O, Cl and S surrounding rock environment for a long time, resulting serious pitting corrosion and spalling of the surface material of the steel strand, which reduces the outer diameter of the rock cable and its bearing capacity, finally leads to the instantaneous SCC fracture of the sample S-6.