Abstract：Rock bridge fracture among multi-crack is one of the important reasons for rock mass failure. If the crack distribution near a rock bridge is known，it is the prerequisite to predict or refrain the failure of this kind of rock mass that the patterns，mechanism of failure and loading conditions are foreknown. These can be essentially obtained by the distribution analyses of the stress and strain extreme values near the crack tips according to the theory of fracture mechanics. The main result is that when the directions of the extreme values of two adjacent cracks are nearly towards each other，these two cracks will link together definitely and result in the rock bridge failure. The properties of the two extreme values determine the properties of the rock bridge fracture.
