The displacement of tunnel during construction and operation is space vector. Usually, the displacement monitoring data in different direction are analyzed to establish the monitoring model separately. In order to know the developing rule of tunnel displacement more completely and truly, base on the analysis of displacement space vector formation, the monitoring model form has been discussed. Then the multidependent variable stepwise regression is used to establish the monitoring model of tunnel displacement space vector, and its calculation progress and instance have been presented, and the differences from single direction displacement model are explained.