Allfibertype sideviewing opticalcoherencetomography (OCT) probe has attracted extensive interests in both academic and industry because of its ultrasmall size and the ability of fullcircumferential imaging. In this manuscript, the design of allfibertype sideviewing OCT probe is optimized for better focusing performance by numerical simulation. Furthermore, the robustness of the optimized allfibertype sideviewing OCT probe versus the size of probe tube and the position of reflector is numerically analyzed for the power fading resulting from the random transverse displacement between reflector and GRIN fiber.