To study the effects of the elastic deformation of flexible paraboloid antenna on the approximate phase center in the stage of attitude adjustments, the mathematical model for solution paraboloid antenna dynamic geometric focus was established and its dynamic response characteristics were solved numerically. The FE model composed of the central platform, solar panels and paraboloid antenna was established and the natural frequencies and mode shapes of the antenna in unconstrained state were calculated. Then through co-simulation of FEM and ADAMS the zero-order rigid-flexible coupling dynamic model of the spacecraft was established, and the dynamic response of the antenna geometric focus in the process of attitude adjustments were obtained. Results show that the flexible attachments elastic vibration accompanves with rigid motions in the procedure of attitude adjustments, and the geometrical focus shock in the equilibrium position reduces spaceborne antenna pointing accuracy to some extent.