A novel dual-mode large-mode-area micro-structured fiber is proposed. The characteristics of mode field distribution, effective area of fundamental mode, and bending loss based on FEM (finite element method) are analyzed. And the effects of all structured parameters on the confinement loss and effective area are discussed. Results show that this structure makes the first HOM (LP11) and the second mode(EH11) cut off, and it achieves dual-mode transmission in the fiber by adjusting the structural parameters. The effective area of a fundamental mode is approximately 700 μm2. The dual-mode large-mode-area micro-structured fiber can be used in large-capacity fiber transmission.