Abstract　  

    Recent advances in radio astrometry with the VLBI have produced images with angular resolution of order 100 as, the absolute and relative astrometric accuracies have yielded about 10-100 as and 1-10 ?as respectively, the site position of radio telescope can be measured better than 1 mm, and vertical atmospheric delay measurement exceeding 10 ps can also be achieved. These unique capabilities of extremely high accuracy VLBI astrometry have led to wide-ranging application in astrophysics and geophysics. In my talk, I will introduce 3 ambitious projects of extremely high accuracy VLBI astrometry (MCP，BeSSeL and PSR ) and review preliminary astrophysical results, including measurement of the Hubble constant, the masses of the massive black holes, the bar and spiral structure of the Milky Way, the accurate distances of pulsars and so on. I will also discuss future applications of extremely high accuracy VLBI astrometry in astrophysics.