Recently, optical waveguides implementation on the substrate has been developed due to the requirement for large capacity and high-speed transmission. Considering that an optical circuit on the substrate must be assembled in a limited space, the integration of the circuit is one of the most important issues for the design of the optical circuits. In optical circuits, a Y-branch waveguide is a basic element of circuits and the length of the Y-branch waveguide depends on its branch angle. To achieve the high density integration of optical circuits, a wide angle Y-branch module, which is a small module, is highly desired. In this paper, we propose a new Y-branch waveguide using reflection at the inclined side-wall of the waveguide. The results of the numerical analysis show the efficiency of the proposed Y-branch waveguide, namely low-los and wide branching, in optical waveguide. Moreover, this paper also discuss that the proposed model is tolerable to the fabrication error comparing to the conventional Y-branch waveguide.