Abstract: The latest domestic and oversea developments of in vivo micro medical robots driven by exterior magnetic field are introduced, and their working principles are analyzed. The analysis result indicates that the drive and control method ~using exterior magnetic field is an effective way and key technology for enhancing the applicability of in vivo micro medical robots. According to the actuality of our micro swimming robot driven by exterior magnetic field, the existing problems related to untethered micro robots driven by exterior magnetic field are exposed. Finally, the key technologies for their practical application and development trends are discussed.