The strain-induced magnetoresistance (MR) has been investigated in detail by simulating the spin-rotation in spin-valve structures. The results show that the strain-induced anisotropy can be utilized to control the relative orientation of the spins in the two adjacently arranged ferromagnetic layers because each layer responds to the external strain differently, thus the strain-induced MR is exhibited. The MR dependencies on magnitude and orientation of strain have been described in detail. Especially, we highlight first the behavior of MR induced by the direction of strain with respect to the magnetic easy axis. In addition, the effects of some magnetic parameters on strain-induced MR have been presented, respectively. This work clarifies further the strain-induced MR mechanism to provide a theoretical support both for a number of experiments and for the design of the MR strain sensors.