Abstract: Renew and maintain of the geodetic coordinate system need not only the continuous monitoring or repeated measuring,but also the reasonable data processing principle and method.The influences of different adjustment methods,including classical adjustment,sequential adjustment and adaptive sequential adjustment,on the datum or the coordinate system are analyzed,a GPS monitoring network is employed to analyze the datum changes due to applying the different adjustment principles.It is shown that sequential adjustment will distort the datum when some of the prior positions have significant deformation.The adaptive sequential adjustment,however,controls the influences of the outliers existing the prior coordinates,thus keeps the datum reliable and reflecting the present position.