A dualmode largemodearea multicore optical fiber is proposed in this paper, and the electromagnetic field model of the proposed fiber is constructed and solved by the finite element method. Both the mode and the bending characteristics of optical fiber are studied based on the model. The influence of the three parameters of core pitch, core radius and refractive index difference between core and cladding on the mode characteristics and effective mode field area of the fiber is analyzed systematically. The proposed multicore fiber can realize strict dualmode transmission by using air holes and reducing the core pitch, core radius and refractive index difference between core and cladding. When the optical fiber maintains dual mode transmission, the area of the mode field of the fundamental mode will increase with the increasing core pitch and decreasing fiber cores radius and the refractive index difference between core and cladding. If the dualmode transmission is approximatively met, the mode field area of the fundamental modes of the straight fiber can reach 3155μm2 by adjusting the structural parameters.