Abstract: Development of time-domain astronomy has been accelerated in recent years, owing to the advance of wide-field optical and radio surveys, as well as applications of new observing techniques that have led to the discoveries of gravitational waves and neutrinos of extragalactic origin. The properties and the nature of many of the new classes of transient sources remain unclear, which are found to be associated with peculiar supernovae, mergers of compact (NS-NS) objects, or tidal disruption events. Another interesting class of short-term transients uniquely observed in radio band is Fast Radio Bursts (FRBs), discovered only ten years ago. Nowadays, the detection is boosted by a factor of 10 with the SKA pathfinders (e.g., ASKAP, CHIME), enabling breakthrough in FRB study. However, the physical origin of FRB remains obscure. One of the mysteries in the transient study is the accurate localization and their physical association with counterparts at other bands. Very long baseline interferometry (VLBI) offers the highest angular resolution among the current astronomical observational techniques, thus plays a vital role in exploring the physical nature of transients and tracing their structural evolution. I will report an overview df the recent high-resolution observations of transients using VLBI. All these prompt to broaden the understanding of fundamental physics.