Abstract: Main mathematic models used in lage scale data processing of combined adjustment of national astro-geodetic network and GPS2000 network are discussed,an effective arithme-tic for large scale sparse matrix resolution also introduced here.Helmert covariance compo-nent estimation is used in estimating covariance component of territory network.Through combined adjustment of these two networks,the avarage mean square error of 48 919 points location is 0.11 m and 95.5% of which is better than 0.3 m.