Abstract: For the anti-inclined rock slope with a group of fissures, a mechanical method for its stability is proposed. At first, based on the bearing mode on the rock block, a fracture mechanics model is established. Through fracture mechanics, a method of the equivalent stress intensity factors for rock blocks and the relevant stability criteria are presented. By introducing the Kelvin creep mode, the methods for the equivalent stress intensity factors and length for fissure of the rock blocks at any time are obtained. It may provide a theoretical basis for controlling and monitoring the anti-inclined rock slope. Then taking the rotation angles of the rock blocks for relation variables, the interaction force between the rock blocks after rotation is quantified, and the relevant method is put forward. At last, through an example, the results calculated by the proposed method for anti-inclined rock slopes agree with the actual situations.