A novel optical fiber system composed of single-mode optical fiber and few mode step-index optical fiber is investigated. The relationship between the core radius and index difference for the few mode optical fiber with the same mode field diameter is analyzed using the finite-element method. The low bending loss characteristics of the few mode optical fiber is also demonstrated. The splicing losses of the few-mode optical fiber with the single-mode optical fiber are investigated by the beam propagation method. Numerical results demonstrate the low bending loss transmission and effectively single-mode guiding using the few-mode optical fiber.