Abstract: In view of the adequate embedded depth is very important to cantilever bracing structure for excavation,and the stability problem of excavation is a fuzzy-random event which includes random and fuzzy failure characteristics,the optimization analysis for embedded depth was studied based on the fuzzy probability theory.The example's results indicated that the fuzzy failure probability would decrease with the increasing of the embedded depth,and therefore,the embedded depth of cantilever bracing structure for excavation could be determined rationally,which satisfied the safety and economical requests.