We present a large effective area fiber design using dual-shape core (DSC) fiber. The fiber is essentially a depressed-index clad fiber with a dual-shape-core consisting of a large central core and a small slightly lower-index side core. The refractive indices of the two cores are so chosen as to perfectly guide the fundamental mode. All the higher-order modes of the fiber are leaky. The fiber shows large-mode-area single-mode operation by higher-order modes discrimination. We have analyzed the structure by using the transfer matrix method. Our numerical simulation results suggest that the DSC fiber can have single-mode operation with effective mode area as large as $580{\mathrm{\mu m}}^2$ and low bending loss. The bending loss of the fiber could be brought down by more than 2 orders of magnitude compared to the corresponding step-index fiber. We also show that the mode field area is relatively insensitive to design param eters in comparison to the leakage loss of the mode. The fiber is amenable to fabrication by modified chemical vapor deposition technology and is expected to find applications in high power fiber lasers and amplifiers.