An LCoS (Liquid Crystal on Silicon) using dielectric protrusions to eliminate fringe field effect is proposed. The dielectric protrusion structure is designed between the pixel electrodes to block the crosstalk electric field between the adjacent pixel electrodes. The liquid crystal molecular director distribution and fringe field crosstalk of the LCoS are simulated, the mechanism of fringe field effect and its influencing factors are analyzed, and the corresponding reflectivity and phase are calculated and compared. The LCoS with dielectric protrusions has a significant effect on eliminating the edge reflectance and phase interference of adjacent pixels compared to the traditional LCoS. The reflectance is always maintained at 96%, the phase difference remains unchanged, areas with contrast greater than 35∶1 are over to 60° and the overall viewing angle is largely unaffected. The proposed dielectric protrusion can eliminate the influence of the transverse electric field on the orientation of liquid crystal molecules in adjacent pixels, which improves the contrast of LCoS and greatly improves the display effect.