Fatigue crack growths of a corner crack emanating from a pinhole of a solid cylinder subjected to cyclic torsion loading were simulated using a Dual-Boundary Element Method (DBEM) based software. For a given crack aspect ratio a/c, larger Mode I stress intensity factor (SIF) was observed at a larger pinhole diameter. Any given initial crack aspect ratio a/c would evolve towards unity. The final evolving crack aspect ratio a/c was shown to be larger than 1. For the same given initial crack length a, a smaller crack depth c was found to result in a shorter fatigue life. A shorter fatigue life yielded a larger orientation angle of the crack growth path.