Parameter errors of the interferometric synthetic aperture radar (InSAR) system influence the vertical accuracy significantly.In this paper

the error sources of the InSAR system is analyzed and classified according to their properties

then the height error model is derived.Using the ground control points(GCPs) and the height error model

a systematic height error arrangement in the whole swath can be obtained with the least-squares method.Based on the error properties

the systematic height error contributions of constant systematic error and slowly changed systematic error can be abstracted from the whole systematic height error

and the baseline error can be derived.The simulation demonstrates the validity of this method.