Abstract：Ice clouds are a critical component of the Earth’s weather and climate system. The orientation of ice crystals influences the scattering properties of these clouds, subsequently impacting the accuracy of remote sensing and numerical weather prediction. With the advancement of dedicated satellite programs for ice cloud observation, precise quantification of ice crystal orientation is becoming increasingly important. This review summarizes research progress in the remote sensing of ice crystal orientation. Both active and passive remote sensing techniques are systematically reviewed for their application across various spectral bands. The detection mechanisms, advantages, and disadvantages of diverse remote sensing techniques are analyzed, with particular emphasis on the prospects of spaceborne terahertz radiometers. While existing techniques demonstrate some capacity for ice crystal orientation studies, quantitative retrievals remain challenging due to ice crystal complexity, observational constraints, and limitations in retrieval algorithms. Finally, future research directions are discussed, focusing on the development of novel detection instrumentation, accurate calculation of ice crystal scattering properties, optimization of radiative transfer modeling, and the synergistic integration of multi-source remote sensing datasets.