The frequency of terahertz wave is in the range of 0.1~10 THz （wavelength 3 mm~30 μm）， which is located between the microwave and infrared bands. Its wavelength is similar to the size of typical ice cloud particles， and it has great potential in ice cloud remote sensing. Terahertz region is expected to have a promising prospect concerning measuring cirrus microphysical parameters， which has broad application prospects and application values for Terahertz wave passive remote sensing of ice clouds. Firstly， the basic principle of terahertz remote sensing of ice clouds was summarized. Then， the key technologies were introduced in detail from three aspects， including the measurement instrument， the forward radiative transfer model and the inversion method of the terahertz remote sensing of ice clouds. In particular， the key parameters of the existing terahertz radiometers， the characteristics of terahertz radiative transfer simulators and the advantages and disadvantages of different inversion methods were discussed and analyzed. Finally， the summary and prospect of the terahertz remote sensing of ice clouds were proposed， in order to provide a reference for the future research of terahertz wave passive remote sensing of ice clouds.