During the 3D seismic acquisition in Ledong area, South China Sea, SkyFix XP positioning system was used to measure real-time geodetic altitude of GPS antenna point for the seismic vessel, and then the real-time tide data during the seismic acquisition was calculated by altitude transformation.

The plane position and geodetic height of peak or target of Qomolangma corresponding to ellipsoid was obtained separately through triangulation network adjustment and height adjustment when processing traditional survey data in Qomolangma height measurement before.

The determination of geodetic height at the Qomolangma peak is one of the very important tasks in the 2005 Qomolangma measurements.

This article mainly discussed some problems about the conversion from geodetic height to normal height, the limitation of calculating height with GPS analog integration method, and how to decide the height problem with the help of gravity, existing surveying and mapping material, and accurate geodetic level through precising GPS control surveying.

The ellipsoidal height can be converted into normal height using the height of GPS leveling, its fitting precision will be impacted mainly by the errors of known point elevation the ellipsoidal height of GPS points and the quasigeoid.

By GPS positioning, we can obtain the three-dimensional coordinates of stations: latitude B, longitude L and ellipsoidal height H.

The high accurate ellipsoidal height according to WGS-84 can be obtained through the adjustment of GPS net,while in engineering application ellipsoidal height needs to be converted to normal height.

The study of obtaining normal height by using GPS geodetic height indirectly is of important significance in railway survey.

In this paper, a new method to solve the problem of transforming GPS geodetic height into normal height by using the linear regression theory has been presented.