The fracture behavior of tilt Cu-Bi tricrystals were studied and a contrast with that of Cu-Bi bicrystals was made. The results indicate that the triple junction affected the fracture behaviors of Cu-Bi tricrystals and made a grain boundary exhibit different fracture modes in bicrystal and tricrystal,The high internal stress near triple junction produced incompatibility of plastic deformation, as well as appearing of inhomogeneity of platic glide and lattice rotation. These are discussed by calculating stress field near triple junction.