Abstract: The requirement of observation precision of pulsar astrometric parameters including the position, proper motion and parallax by VLBI technique is analyzed based on the fundamental principle of pulse timing observations and the application in deep space navigation of millisecond pulsars. It is also discussed concerning the current technical specifications, the deficiencies as well as the possible ways of improvement in the equipment of electronic backend of antennas, the data cross-correlation processing and the time synchronization of the Chinese VLBI network on the observation of millisecond pulsars for criticism and reference.