A novel optical power splitter (OPS) based on a nonperiodic subwavelength high-index-contrast grating (HCG) is proposed. The OPS can split the reflected light into two beams while maintaining a high reflectivity. In order to achieve a specific phase-shift distribution for the application mentioned above, a rigorous coupled-wave analysis (RCWA) is used to calculate the reflectivity and phase shift of a periodic subwavelength HCG while changing the grating period and duty cycle to obtain the proper structural parameters of the HCG. The properties of the two-port OPS are numerically studied with a finite element method (FEM), which exhibits a 3.27 dB insertion loss and a wavelength varying from 1.50 to 1.60 μm. The presented OPS can be easily integrated with a semiconductor device.