A high-efficiency grating coupler is designed for vertical coupling between silicon-on-insulator waveguides and single-mode fibers. The reflection characteristics of reflector grating and distributed bragg reflector are employed to obtain a high reflection from the right side and bottom of the coupler. The reflected light is interfered destructively to reduce the negative second-order reflection by selecting a reasonable spacing between the reflector grating and the coupler grating when the coupler grating is in the vertical coupling. The coupler is optimized using eigenmode expansion-based simulations. The highest coupling efficiency of 89% at a wavelength 1 550 nm is achieved by simulation. The results provide some useful references for the fabrication of the actual vertical coupling grating coupler.