Faraday effect is a magneto-optic effect which closely linkes physical quantities such as light, electricity and magnetic. Magneto-optic modulation technique based on Faraday effect is widely used because of strong antijamming, high precision, small volume, light weight, etc. On the basis of a summary of magneto-optic modulation technology literature, the basic principle of magneto-optic modulation technology is introduced. The applications of magneto-optic modulation technology in the fields of azimuth benchmark transfer, precision angle measurement, material performance research, industrial parameter measurement, biochemistry, etc are introduced at home and abroad in detail. Key technologies of precision optimization and reliability improvement in magneto-optic modulation are emphatically analyzed. Finally, the future research hot spot in this technology is discussed.