The VLBI relativistic time delay model of transformation is reformuled with a precision of better than 1 ps, which is given as follows

where is geocentric newtonial potential, and are the barycentric velocity vector in B-frame and the geocentric velocity vector of antenna i. Ŝ is the unit vector of the direction from the barycenter of solar system to the source. c is the speed of light in vacuum. , where is the geocentric baseline vector. δtv can be expressed as in which and

where Δtatm, Δtion and Δtaxo are the tropospheric, the ionospheric and the axio offset refraction delays respectively, and Δtgrav is called the gravitational time delay. A straightforward differentation of expression (1), the equation of d(dτ)/dt can be obtained. The included in the can be expressed as

The orders of magnitude of the various correction terms in expression (4) and (5) are estimated respectively. Conclusion: expression (4) and (5) should be taken into account in the VLBI relativistic model of transformation for the 1 ps precision. Equation (1) and the expression of its differentation differ from all the models which have been published earlier.