Abstract: The gravity gradiometer is formed by 3 pairs of electrostatic suspension accelerometers.The accelerometer reference frame must be converted into gradiometer reference frame in order to calculate gravity gradient from accelerometers. In this paper, the definitions of each reference frame in the gradiometer are described and specific measurement and construction methods for each reference system are proposed for actual measurement problems.The gradiometer under research had been measured using three-coordinate measurement system in order to construct each reference frame one by one. At last, some enlightenment on design and assembly in view of the above research is summarized, suggestions are made for the future design and development of high-precision gradiometer, and the follow-up research on the future reference frame transformation is envisaged.