In this paper, the simulated mathematical models of the panda fiber of matching refractive-index (MRI) were given through the structure of the fiber and the physics principles of phase contrast. Computer simulation of phase contrast alignment of birefringent axes (BA) in the panda fiber was done. Simulated mathematical models include several physics principles, e.g., distribution of stress-induced refractive index in the panda fiber of MRI, phase contrast, and image error of optical fiber around the observation plane of the objective lens. Computer simulation gave the optical intensity distinguishing profile in phase contrast to align BA in the panda fiber of MRI. The simulated profiles fit well with experimental ones. The technique has been used in experiments and the resolving power was less than two degrees.