Optimal multiple motion encoding (OMME) for phase-contrast MRI was developed with application to magnetic resonance elastography for unwrapping motion images. OMME is formulated as a least-squares problem using multiple phase-contrast measurements with different motion encoding gradients (MEG). OMME is applied to phantom and in vivo human brain experiments. The wrap-free motion images are further used to reconstruct shear-wave-speed maps and compared to conventional phase unwrapping methods. OMME generates wrap free phase-contrast images with the wrap limit determined by the smallest MEG used, while maintaining the signal-to-noise ratio(SNR) of the largest MEG, which makes OMME especially suitable for high SNR applications.